CC filesystem_xfs@kernel-bugs.kernel.org

Default xfs (no specified mkfs options) can reproduce this bug with xfstests xfs/294. The decode_stacktrace.sh output as below[1], HEAD=032dcf09e ("Merge tag 'gpio-fixes-for-v5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/brgl/linux")

[1]
# ./scripts/decode_stacktrace.sh vmlinux < console.log
[30523.215443] run fstests xfs/294 at 2022-06-05 00:40:48
[30525.371171] XFS (loop1): Mounting V5 Filesystem
[30525.388258] XFS (loop1): Ending clean mount
[30574.012385] restraintd[1854]: *** Current Time: Sun Jun 05 00:41:38 2022  Loc
alwatchdog at: Mon Jun 06 16:13:37 2022
[30604.239628] usercopy: Kernel memory exposure attempt detected from vmalloc 'n
o area' (offset 0, size 1)!
[30604.239677] ------------[ cut here ]------------
[30604.239679] kernel BUG at mm/usercopy.c:101!
[30604.239731] monitor event: 0040 ilc:2 [#1] SMP
[30604.239774] Modules linked in: ext2 overlay dm_zero dm_log_writes dm_thin_poo
l dm_persistent_data dm_bio_prison sd_mod t10_pi crc64_rocksoft_generic crc64_ro
cksoft crc64 sg dm_snapshot dm_bufio ext4 mbcache jbd2 dm_flakey tls loop lcs ct
cm fsm zfcp scsi_transport_fc dasd_fba_mod rfkill vfio_ccw mdev vfio_iommu_type1
zcrypt_cex4 vfio sunrpc drm i2c_core fb fuse font drm_panel_orientation_quirks
xfs libcrc32c ghash_s390 prng aes_s390 des_s390 sha3_512_s390 sha3_256_s390 qeth
_l2 bridge stp llc dasd_eckd_mod dasd_mod qeth qdio ccwgroup dm_mirror dm_region
_hash dm_log dm_mod pkey zcrypt [last unloaded: scsi_debug]
5.18.0+ #1
[30604.240048] Hardware name: IBM 8561 LT1 400 (z/VM 7.2.0)
[30604.240155] Krnl PSW : 0704d00180000000 00000000255ca85a (usercopy_abort+0xaa
/0xb0)
[30604.240177]            R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:1 PM:0 RI:
0 EA:3
[30604.240188] Krnl GPRS: 0000000000000001 001c000018090e00 000000000000005c 000
0000000000004
[30604.240196]            001c000000000000 00000000249b2024 00000000257cb1a0 001
bff8000000000
[30604.240204]            0000000000000001 0000000000000001 0000000000000000 000
00000257cb1e0
[30604.240213]            0000000025d8d070 00000000973502c0 00000000255ca856 001
bff80041af730
[30604.240231] Krnl Code: 00000000255ca84c: b9040031 lgr %r3,%r1

Code starting with the faulting instruction
===========================================
[30604.240231]            00000000255ca850: c0e5ffffbbfc        brasl   %r14,000
00000255c2048
[30604.240231]           #00000000255ca856: af000000            mc      0,0
[30604.240231]           >00000000255ca85a: 0707                bcr     0,%r7
[30604.240231]            00000000255ca85c: 0707                bcr     0,%r7
[30604.240231]            00000000255ca85e: 0707                bcr     0,%r7
[30604.240231]            00000000255ca860: c0040007b0a4        brcl    0,000000
00256c09a8
[30604.240231]            00000000255ca866: eb6ff0480024        stmg    %r6,%r15
,72(%r15)
[30604.240369] Call Trace:
[30604.240375] usercopy_abort (??:?) 
[30604.240382] usercopy_abort (mm/usercopy.c:101 (discriminator 24)) 
[30604.240400] check_heap_object (mm/usercopy.c:180) 
[30604.240409] __check_object_size (mm/usercopy.c:123 mm/usercopy.c:255 mm/usercopy.c:214) 
[30604.240415] filldir64 (./include/linux/uaccess.h:108 fs/readdir.c:339) 
[30604.240424] xfs_dir2_leaf_getdents (./include/linux/fs.h:3430 fs/xfs/xfs_dir2_readdir.c:472) xfs
[30604.240830] xfs_readdir (fs/xfs/xfs_dir2_readdir.c:547) xfs
[30604.241036] iterate_dir (fs/readdir.c:65) 
[30604.241042] __do_sys_getdents64 (fs/readdir.c:369) 
[30604.241047] do_syscall (arch/s390/kernel/syscall.c:144 (discriminator 1)) 
[30604.241053] __do_syscall (arch/s390/kernel/syscall.c:169) 
[30604.241058] system_call (arch/s390/kernel/entry.S:335) 
[30604.241064] INFO: lockdep is turned off.
[30604.241067] Last Breaking-Event-Address:
[30604.241070] _printk (kernel/printk/printk.c:2426) 
[30604.241077] ---[ end trace 0000000000000000 ]---
[30609.984847] usercopy: Kernel memory exposure attempt detected from vmalloc 'n
o area' (offset 0, size 1)!
[30609.984894] ------------[ cut here ]------------
[30609.984896] kernel BUG at mm/usercopy.c:101!
[30609.984945] monitor event: 0040 ilc:2 [#2] SMP
[30609.984984] Modules linked in: ext2 overlay dm_zero dm_log_writes dm_thin_poo
l dm_persistent_data dm_bio_prison sd_mod t10_pi crc64_rocksoft_generic crc64_r
cksoft crc64 sg dm_snapshot dm_bufio ext4 mbcache jbd2 dm_flakey tls loop lcs ct
cm fsm zfcp scsi_transport_fc dasd_fba_mod rfkill vfio_ccw mdev vfio_iommu_type1
zcrypt_cex4 vfio sunrpc drm i2c_core fb fuse font drm_panel_orientation_quirks
xfs libcrc32c ghash_s390 prng aes_s390 des_s390 sha3_512_s390 sha3_256_s390 qeth
_l2 bridge stp llc dasd_eckd_mod dasd_mod qeth qdio ccwgroup dm_mirror dm_region
_hash dm_log dm_mod pkey zcrypt [last unloaded: scsi_debug]
5.18.0+ #1
[30609.985151] Hardware name: IBM 8561 LT1 400 (z/VM 7.2.0)
[30609.985211] Krnl PSW : 0704d00180000000 00000000255ca85a (usercopy_abort+0xaa
/0xb0)
[30609.985249]            R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:1 PM:0 RI:
0 EA:3
[30609.985258] Krnl GPRS: 0000000000000001 001c000018090e00 000000000000005c 000
0000000000004
[30609.985264]            001c000000000000 00000000249b2024 00000000257cb1a0 001
bff8000000000
[30609.985271]            0000000000000001 0000000000000001 0000000000000000 000
00000257cb1e0
[30609.985276]            0000000025d8d070 00000000a2d652c0 00000000255ca856 001
bff800810f668
[30609.985293] Krnl Code: 00000000255ca84c: b9040031 lgr %r3,%r1

Code starting with the faulting instruction
===========================================
[30609.985293]            00000000255ca850: c0e5ffffbbfc        brasl   %r14,000
00000255c2048
[30609.985293]           #00000000255ca856: af000000            mc      0,0
[30609.985293]           >00000000255ca85a: 0707                bcr     0,%r7
[30609.985293]            00000000255ca85c: 0707                bcr     0,%r7
[30609.985293]            00000000255ca85e: 0707                bcr     0,%r7
[30609.985293]            00000000255ca860: c0040007b0a4        brcl    0,000000
00256c09a8
[30609.985293]            00000000255ca866: eb6ff0480024        stmg    %r6,%r15
,72(%r15)
[30609.985340] Call Trace:
[30609.985345] usercopy_abort (??:?) 
[30609.985352] usercopy_abort (mm/usercopy.c:101 (discriminator 24)) 
[30609.985358] check_heap_object (mm/usercopy.c:180) 
[30609.985367] __check_object_size (mm/usercopy.c:123 mm/usercopy.c:255 mm/usercopy.c:214) 
[30609.985374] filldir64 (./include/linux/uaccess.h:108 fs/readdir.c:339) 
[30609.985383] xfs_dir2_leaf_getdents (./include/linux/fs.h:3430 fs/xfs/xfs_dir2_readdir.c:472) xfs
[30609.985780] xfs_readdir (fs/xfs/xfs_dir2_readdir.c:547) xfs
[30609.986002] iterate_dir (fs/readdir.c:65) 
[30609.986009] __do_sys_getdents64 (fs/readdir.c:369) 
[30609.986017] do_syscall (arch/s390/kernel/syscall.c:144 (discriminator 1)) 
[30609.986026] __do_syscall (arch/s390/kernel/syscall.c:169) 
[30609.986033] system_call (arch/s390/kernel/entry.S:335) 
[30609.986041] INFO: lockdep is turned off.
[30609.986046] Last Breaking-Event-Address:
[30609.986050] _printk (kernel/printk/printk.c:2426) 
[30609.986059] ---[ end trace 0000000000000000 ]---
[30610.050449] XFS (loop0): Unmounting Filesystem

(switched to email.  Please respond via emailed reply-to-all, not via the
bugzilla web interface).

On Sun, 05 Jun 2022 01:00:15 +0000 bugzilla-daemon@kernel.org wrote:

> https://bugzilla.kernel.org/show_bug.cgi?id=216073
> 
>             Bug ID: 216073
>            Summary: [s390x] kernel BUG at mm/usercopy.c:101! usercopy:
>                     Kernel memory exposure attempt detected from vmalloc
>                     'n  o area' (offset 0, size 1)!
>            Product: Memory Management
>            Version: 2.5
>     Kernel Version: 5.19-rc0
>           Hardware: All
>                 OS: Linux
>               Tree: Mainline
>             Status: NEW
>           Severity: normal
>           Priority: P1
>          Component: Other
>           Assignee: akpm@linux-foundation.org
>           Reporter: zlang@redhat.com
>         Regression: No
> 
> Recently xfstests on s390x always hit below kernel BUG:
>  usercopy: Kernel memory exposure attempt detected from vmalloc 'no area'
> (offset 0, size 1)!

Thanks.  Do you know if this is specific to s390?


> It's reproducible on xfs with default mkfs options. But it's easier and 100%
> reproducible (for me) on xfs with 64k directory block size (-n size=65536).
> 
> The kernel HEAD commit is:
> commit 032dcf09e2bf7c822be25b4abef7a6c913870d98
> Author: Linus Torvalds <torvalds@linux-foundation.org>
> Date:   Fri Jun 3 20:01:25 2022 -0700
> 
>     Merge tag 'gpio-fixes-for-v5.19-rc1' of
> git://git.kernel.org/pub/scm/linux/kernel/git/brgl/linux
> 
> 
> [20797.425894] XFS (loop1): Mounting V5 Filesystem                            
> [20797.433354] XFS (loop1): Ending clean mount                                
> [20823.669300] usercopy: Kernel memory exposure attempt detected from vmalloc
> 'n 
> o area' (offset 0, size 1)!                                                   
> [20823.669339] ------------[ cut here ]------------                           
> [20823.669340] kernel BUG at mm/usercopy.c:101!                               
> [20823.669385] monitor event: 0040 ilc:2 [#1] SMP                             
> [20823.669415] Modules linked in: ext2 overlay dm_zero dm_log_writes
> dm_thin_poo 
> l dm_persistent_data dm_bio_prison sd_mod t10_pi crc64_rocksoft_generic
> crc64_ro 
> cksoft crc64 sg dm_snapshot dm_bufio ext4 mbcache jbd2 dm_flakey tls loop lcs
> ct 
> cm fsm zfcp scsi_transport_fc dasd_fba_mod rfkill sunrpc vfio_ccw mdev
> vfio_iomm 
> u_type1 zcrypt_cex4 vfio drm fuse i2c_core fb font
> drm_panel_orientation_quirks 
> xfs libcrc32c ghash_s390 prng aes_s390 des_s390 sha3_512_s390 sha3_256_s390
> dasd 
> _eckd_mod dasd_mod qeth_l2 bridge stp llc qeth qdio ccwgroup dm_mirror
> dm_region 
> _hash dm_log dm_mod pkey zcrypt [last unloaded: scsi_debug]                   
> [20823.669520] CPU: 0 PID: 3774731 Comm: rm Kdump: loaded Tainted: G    B   W 
>       5.18.0+ #1                                                              
> [20823.669530] Hardware name: IBM 8561 LT1 400 (z/VM 7.2.0)                   
> [20823.672501] Krnl PSW : 0704d00180000000 000000009df4a85a
> (usercopy_abort+0xaa 
> /0xb0)                                                                        
> [20823.672564]            R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:1 PM:0
> RI: 
> 0 EA:3                                                                        
> [20823.672575] Krnl GPRS: 0000000000000001 001c000018090e00 000000000000005c
> 000 
> 0000000000004                                                                 
> [20823.672584]            001c000000000000 000000009d332024 000000009e14b1a0
> 001 
> bff8000000000                                                                 
> [20823.672593]            0000000000000001 0000000000000001 0000000000000000
> 000 
> 000009e14b1e0                                                                 
> [20823.672601]            000000009e70d070 00000000a87bdac0 000000009df4a856
> 001 
> bff8001f5f720                                                                 
> [20823.672621] Krnl Code: 000000009df4a84c: b9040031            lgr    
> %r3,%r1 
> [20823.672621]            000000009df4a850: c0e5ffffbbfc        brasl  
> %r14,000 
> 000009df42048                                                                 
> [20823.672621]           #000000009df4a856: af000000            mc      0,0   
> [20823.672621]           >000000009df4a85a: 0707                bcr     0,%r7 
> [20823.672621]            000000009df4a85c: 0707                bcr     0,%r7 
> [20823.672621]            000000009df4a85e: 0707                bcr     0,%r7 
> [20823.672621]            000000009df4a860: c0040007b0a4        brcl   
> 0,000000 
> 009e0409a8                                                                    
> [20823.672621]            000000009df4a866: eb6ff0480024        stmg   
> %r6,%r15 
> ,72(%r15)                                                                     
> [20823.672789] Call Trace:                                                    
> [20823.672794]  [<000000009df4a85a>] usercopy_abort+0xaa/0xb0                 
> [20823.672817] ([<000000009df4a856>] usercopy_abort+0xa6/0xb0)                
> [20823.672825]  [<000000009cd30c34>] check_heap_object+0x474/0x480            
> [20823.672833]  [<000000009cd30cb4>] __check_object_size+0x74/0x150           
> [20823.672840]  [<000000009cd8de06>] filldir64+0x296/0x530                    
> [20823.672849]  [<001bffff805957dc>] xfs_dir2_leaf_getdents+0x40c/0xca0 [xfs] 
> [20823.673277]  [<001bffff80596e18>] xfs_readdir+0x3f8/0x740 [xfs]            
> [20823.673522]  [<000000009cd8c7ac>] iterate_dir+0x41c/0x580                  
> [20823.673529]  [<000000009cd8d6b4>] __do_sys_getdents64+0xc4/0x1c0           
> [20823.673537]  [<000000009c4bda8c>] do_syscall+0x22c/0x330                   
> [20823.673546]  [<000000009df5e8be>] __do_syscall+0xce/0xf0                   
> [20823.673554]  [<000000009df87402>] system_call+0x82/0xb0                    
> [20823.673563] INFO: lockdep is turned off.                                   
> [20823.673568] Last Breaking-Event-Address:                                   
> [20823.673572]  [<000000009df420f4>] _printk+0xac/0xb8                        
> [20823.673581] ---[ end trace 0000000000000000 ]---                           
> [20829.875273] usercopy: Kernel memory exposure attempt detected from vmalloc
> 'n 
> o area' (offset 0, size 1)!                                                   
> [20829.875316] ------------[ cut here ]------------                           
> [20829.875318] kernel BUG at mm/usercopy.c:101!                               
> [20829.875448] monitor event: 0040 ilc:2 [#2] SMP                             
> [20829.875468] Modules linked in: ext2 overlay dm_zero dm_log_writes
> dm_thin_poo 
> l dm_persistent_data dm_bio_prison sd_mod t10_pi crc64_rocksoft_generic
> crc64_r 
> cksoft crc64 sg dm_snapshot dm_bufio ext4 mbcache jbd2 dm_flakey tls loop lcs
> ct 
> cm fsm zfcp scsi_transport_fc dasd_fba_mod rfkill sunrpc vfio_ccw mdev
> vfio_iomm 
> u_type1 zcrypt_cex4 vfio drm fuse i2c_core fb font
> drm_panel_orientation_quirks 
> xfs libcrc32c ghash_s390 prng aes_s390 des_s390 sha3_512_s390 sha3_256_s390
> dasd 
> _eckd_mod dasd_mod qeth_l2 bridge stp llc qeth qdio ccwgroup dm_mirror
> dm_region 
> _hash dm_log dm_mod pkey zcrypt [last unloaded: scsi_debug]                   
> [20829.875616] CPU: 0 PID: 3776251 Comm: find Kdump: loaded Tainted: G    B D
> W 
>         5.18.0+ #1                                                            
> [20829.875629] Hardware name: IBM 8561 LT1 400 (z/VM 7.2.0)                   
> [20829.879533] Krnl PSW : 0704d00180000000 000000009df4a85a
> (usercopy_abort+0xaa 
> /0xb0)                                                                        
> [20829.879554]            R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:1 PM:0
> RI: 
> 0 EA:3                                                                        
> [20829.879573] Krnl GPRS: 0000000000000001 001c000018090e00 000000000000005c
> 000 
> 0000000000004                                                                 
> [20829.879578]            001c000000000000 000000009d332024 000000009e14b1a0
> 001 
> bff8000000000                                                                 
> [20829.879583]            0000000000000001 0000000000000001 0000000000000000
> 000 
> 000009e14b1e0                                                                 
> [20829.879587]            000000009e70d070 00000000a21852c0 000000009df4a856
> 001 
> bff8004fef728                                                                 
> [20829.879599] Krnl Code: 000000009df4a84c: b9040031            lgr    
> %r3,%r1 
> [20829.879599]            000000009df4a850: c0e5ffffbbfc        brasl  
> %r14,000 
> 000009df42048                                                                 
> [20829.879599]           #000000009df4a856: af000000            mc      0,0   
> [20829.879599]           >000000009df4a85a: 0707                bcr     0,%r7 
> [20829.879599]            000000009df4a85c: 0707                bcr     0,%r7 
> [20829.879599]            000000009df4a85e: 0707                bcr     0,%r7 
> [20829.879599]            000000009df4a860: c0040007b0a4        brcl   
> 0,000000 
> 009e0409a8                                                                    
> [20829.879599]            000000009df4a866: eb6ff0480024        stmg   
> %r6,%r15 
> ,72(%r15)                                                                     
> [20829.879631] Call Trace:                                                    
> [20829.879634]  [<000000009df4a85a>] usercopy_abort+0xaa/0xb0                 
> [20829.879639] ([<000000009df4a856>] usercopy_abort+0xa6/0xb0)                
> [20829.879644]  [<000000009cd30c34>] check_heap_object+0x474/0x480            
> [20829.879650]  [<000000009cd30cb4>] __check_object_size+0x74/0x150           
> [20829.879654]  [<000000009cd8de06>] filldir64+0x296/0x530                    
> [20829.879661]  [<001bffff805957dc>] xfs_dir2_leaf_getdents+0x40c/0xca0 [xfs] 
> [20829.879971]  [<001bffff80596e18>] xfs_readdir+0x3f8/0x740 [xfs]            
> [20829.880107]  [<000000009cd8c7ac>] iterate_dir+0x41c/0x580                  
> [20829.880112]  [<000000009cd8d6b4>] __do_sys_getdents64+0xc4/0x1c0           
> [20829.880117]  [<000000009c4bda8c>] do_syscall+0x22c/0x330                   
> [20829.880124]  [<000000009df5e8be>] __do_syscall+0xce/0xf0                   
> [20829.880129]  [<000000009df87402>] system_call+0x82/0xb0                    
> [20829.880135] INFO: lockdep is turned off.                                   
> [20829.880138] Last Breaking-Event-Address:                                   
> [20829.880141]  [<000000009df420f4>] _printk+0xac/0xb8                        
> [20829.880148] ---[ end trace 0000000000000000 ]---                           
> [20829.975537] XFS (loop0): Unmounting Filesystem
> 
> -- 
> You may reply to this email to add a comment.
> 
> You are receiving this mail because:
> You are the assignee for the bug.

On Mon, Jun 06, 2022 at 03:13:12PM -0700, Andrew Morton wrote:
> (switched to email.  Please respond via emailed reply-to-all, not via the
> bugzilla web interface).

Hi Zorro,

Unfortunately, I am not able to reproduce the issue. Could you please
clarify your test environment details and share your xfstests config?

Thanks!

On Tue, Jun 07, 2022 at 05:05:01PM +0200, Alexander Gordeev wrote:
> On Mon, Jun 06, 2022 at 03:13:12PM -0700, Andrew Morton wrote:
> > (switched to email.  Please respond via emailed reply-to-all, not via the
> > bugzilla web interface).
> 
> Hi Zorro,
> 
> Unfortunately, I am not able to reproduce the issue. Could you please
> clarify your test environment details and share your xfstests config?

One of the test environment details as [1]. The xfstests config as [2].
It's easier to reproduce on 64k directory size xfs by running xfstests
auto group.

Thanks,
Zorro

[1]
CPU
Vendor	IBM/S390
Model Name	8561
Family	0
Model	3126312
Stepping	0
Speed	0.0
Processors	2
Cores	0
Sockets	0
Hyper	True
Flags	edat dfp vxp vx vxe ldisp sie vxe2 highgprs etf3eh te vxd gs sort zarch msa stfle dflt eimm esan3
Arch(s)	s390x

Memory	4096 MB
NUMA Nodes	1

Disks
Model	Size	Logical sector size	Physical sector size
3390/0c	41.03 GB / 38.21 GiB	4096 bytes	4096 bytes

[2]
# cat local.config
FSTYP=xfs
TEST_DEV=/dev/loop0
TEST_DIR=/mnt/fstests/TEST_DIR
SCRATCH_DEV=/dev/loop1
SCRATCH_MNT=/mnt/fstests/SCRATCH_DIR
LOGWRITES_DEV=/dev/loop2
MKFS_OPTIONS="-n size=65536 -m crc=1,finobt=1,reflink=1,rmapbt=0,bigtime=1,inobtcount=1"
TEST_FS_MOUNT_OPTS=""

> 
> Thanks!
>

On Wed, Jun 08, 2022 at 10:19:22AM +0800, Zorro Lang wrote:
> One of the test environment details as [1]. The xfstests config as [2].
> It's easier to reproduce on 64k directory size xfs by running xfstests
> auto group.


Thanks for the details, Zorro!

Do you create test and scratch device with xfs_io, as README suggests?
If yes, what are sizes of the files?
Also, do you run always xfs/auto or xfs/294 hits for you reliably?

Thanks!

On Wed, Jun 08, 2022 at 09:13:12PM +0200, Alexander Gordeev wrote:
> On Wed, Jun 08, 2022 at 10:19:22AM +0800, Zorro Lang wrote:
> > One of the test environment details as [1]. The xfstests config as [2].
> > It's easier to reproduce on 64k directory size xfs by running xfstests
> > auto group.
> 
> 
> Thanks for the details, Zorro!
> 
> Do you create test and scratch device with xfs_io, as README suggests?
> If yes, what are sizes of the files?

# fallocate -l 5G /home/test_dev.img
# fallocate -l 10G /home/scratch_dev.img
Then create loop devices.


> Also, do you run always xfs/auto or xfs/294 hits for you reliably?

100% for on my testing, I tried 10 times, then hit it 10 times last
weekend. Will test again this week.

> 
> Thanks!
>

It's not a s390x specific bug, I just hit this issue on aarch64 with linux v5.19.0-rc1:

[  980.200947] usercopy: Kernel memory exposure attempt detected from vmalloc 'no area' (offset 0, size 1)! 
[  980.200968] ------------[ cut here ]------------ 
[  980.200969] kernel BUG at mm/usercopy.c:101! 
[  980.201081] Internal error: Oops - BUG: 0 [#1] SMP 
[  980.224192] Modules linked in: rfkill arm_spe_pmu mlx5_ib ast drm_vram_helper drm_ttm_helper ttm ib_uverbs acpi_ipmi drm_kms_helper ipmi_ssif fb_sys_fops syscopyarea sysfillrect ib_core sysimgblt arm_cmn arm_dmc620_pmu arm_dsu_pmu cppc_cpufreq sunrpc vfat fat drm fuse xfs libcrc32c mlx5_core crct10dif_ce ghash_ce sha2_ce sha256_arm64 sha1_ce sbsa_gwdt nvme igb mlxfw nvme_core tls i2c_algo_bit psample pci_hyperv_intf i2c_designware_platform i2c_designware_core xgene_hwmon ipmi_devintf ipmi_msghandler 
[  980.268449] CPU: 42 PID: 121940 Comm: rm Kdump: loaded Not tainted 5.19.0-rc1+ #1 
[  980.275921] Hardware name: GIGABYTE R272-P30-JG/MP32-AR0-JG, BIOS F16f (SCP: 1.06.20210615) 07/01/2021 
[  980.285214] pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) 
[  980.292165] pc : usercopy_abort+0x78/0x7c 
[  980.296167] lr : usercopy_abort+0x78/0x7c 
[  980.300166] sp : ffff80002b007730 
[  980.303469] x29: ffff80002b007740 x28: ffff80002b007cc0 x27: ffffdc5683ecc880 
[  980.310595] x26: 1ffff00005600f9b x25: ffffdc5681c90000 x24: ffff80002b007cdc 
[  980.317722] x23: ffff800041a0004a x22: 0000000000000001 x21: 0000000000000001 
[  980.324848] x20: 0000000000000000 x19: ffff800041a00049 x18: 0000000000000000 
[  980.331974] x17: 2720636f6c6c616d x16: 76206d6f72662064 x15: 6574636574656420 
[  980.339101] x14: 74706d6574746120 x13: 21293120657a6973 x12: ffff6106cbc4c03f 
[  980.346227] x11: 1fffe106cbc4c03e x10: ffff6106cbc4c03e x9 : ffffdc5681f36e30 
[  980.353353] x8 : ffff08365e2601f7 x7 : 0000000000000001 x6 : ffff6106cbc4c03e 
[  980.360480] x5 : ffff08365e2601f0 x4 : 1fffe10044b11801 x3 : 0000000000000000 
[  980.367606] x2 : 0000000000000000 x1 : ffff08022588c000 x0 : 000000000000005c 
[  980.374733] Call trace: 
[  980.377167]  usercopy_abort+0x78/0x7c 
[  980.380819]  check_heap_object+0x3dc/0x3e0 
[  980.384907]  __check_object_size.part.0+0x6c/0x1f0 
[  980.389688]  __check_object_size+0x24/0x30 
[  980.393774]  filldir64+0x548/0x84c 
[  980.397165]  xfs_dir2_block_getdents+0x404/0x960 [xfs] 
[  980.402437]  xfs_readdir+0x3c4/0x4b0 [xfs] 
[  980.406652]  xfs_file_readdir+0x6c/0xa0 [xfs] 
[  980.411127]  iterate_dir+0x3a4/0x500 
[  980.414691]  __do_sys_getdents64+0xb0/0x230 
[  980.418863]  __arm64_sys_getdents64+0x70/0xa0 
[  980.423209]  invoke_syscall.constprop.0+0xd8/0x1d0 
[  980.427991]  el0_svc_common.constprop.0+0x224/0x2bc 
[  980.432858]  do_el0_svc+0x4c/0x90 
[  980.436163]  el0_svc+0x5c/0x140 
[  980.439294]  el0t_64_sync_handler+0xb4/0x130 
[  980.443553]  el0t_64_sync+0x174/0x178 
[  980.447206] Code: f90003e3 aa0003e3 91098100 97ffe24b (d4210000)  
[  980.453292] SMP: stopping secondary CPUs 
[  980.458162] Starting crashdump kernel... 
[  980.462073] Bye!

Zorro, linux developers don't use buugzilla.  Nobody saw your most
recent comment.

Please resend it, as an emailed reply-to-all.

On Wed, Jun 08, 2022 at 09:13:12PM +0200, Alexander Gordeev wrote:
> On Wed, Jun 08, 2022 at 10:19:22AM +0800, Zorro Lang wrote:
> > One of the test environment details as [1]. The xfstests config as [2].
> > It's easier to reproduce on 64k directory size xfs by running xfstests
> > auto group.
> 
> 
> Thanks for the details, Zorro!
> 
> Do you create test and scratch device with xfs_io, as README suggests?
> If yes, what are sizes of the files?
> Also, do you run always xfs/auto or xfs/294 hits for you reliably?

Looks likt it's not a s390x specific bug, I just hit this issue once (not 100%
reproducible) on aarch64 with linux v5.19.0-rc1+ [1]. So back to cc linux-mm
to get more review.

Thanks,
Zorro

[1]
[  980.200947] usercopy: Kernel memory exposure attempt detected from vmalloc 'no area' (offset 0, size 1)! 
[  980.200968] ------------[ cut here ]------------ 
[  980.200969] kernel BUG at mm/usercopy.c:101! 
[  980.201081] Internal error: Oops - BUG: 0 [#1] SMP 
[  980.224192] Modules linked in: rfkill arm_spe_pmu mlx5_ib ast drm_vram_helper drm_ttm_helper ttm ib_uverbs acpi_ipmi drm_kms_helper ipmi_ssif fb_sys_fops syscopyarea sysfillrect ib_core sysimgblt arm_cmn arm_dmc620_pmu arm_dsu_pmu cppc_cpufreq sunrpc vfat fat drm fuse xfs libcrc32c mlx5_core crct10dif_ce ghash_ce sha2_ce sha256_arm64 sha1_ce sbsa_gwdt nvme igb mlxfw nvme_core tls i2c_algo_bit psample pci_hyperv_intf i2c_designware_platform i2c_designware_core xgene_hwmon ipmi_devintf ipmi_msghandler 
[  980.268449] CPU: 42 PID: 121940 Comm: rm Kdump: loaded Not tainted 5.19.0-rc1+ #1 
[  980.275921] Hardware name: GIGABYTE R272-P30-JG/MP32-AR0-JG, BIOS F16f (SCP: 1.06.20210615) 07/01/2021 
[  980.285214] pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) 
[  980.292165] pc : usercopy_abort+0x78/0x7c 
[  980.296167] lr : usercopy_abort+0x78/0x7c 
[  980.300166] sp : ffff80002b007730 
[  980.303469] x29: ffff80002b007740 x28: ffff80002b007cc0 x27: ffffdc5683ecc880 
[  980.310595] x26: 1ffff00005600f9b x25: ffffdc5681c90000 x24: ffff80002b007cdc 
[  980.317722] x23: ffff800041a0004a x22: 0000000000000001 x21: 0000000000000001 
[  980.324848] x20: 0000000000000000 x19: ffff800041a00049 x18: 0000000000000000 
[  980.331974] x17: 2720636f6c6c616d x16: 76206d6f72662064 x15: 6574636574656420 
[  980.339101] x14: 74706d6574746120 x13: 21293120657a6973 x12: ffff6106cbc4c03f 
[  980.346227] x11: 1fffe106cbc4c03e x10: ffff6106cbc4c03e x9 : ffffdc5681f36e30 
[  980.353353] x8 : ffff08365e2601f7 x7 : 0000000000000001 x6 : ffff6106cbc4c03e 
[  980.360480] x5 : ffff08365e2601f0 x4 : 1fffe10044b11801 x3 : 0000000000000000 
[  980.367606] x2 : 0000000000000000 x1 : ffff08022588c000 x0 : 000000000000005c 
[  980.374733] Call trace: 
[  980.377167]  usercopy_abort+0x78/0x7c 
[  980.380819]  check_heap_object+0x3dc/0x3e0 
[  980.384907]  __check_object_size.part.0+0x6c/0x1f0 
[  980.389688]  __check_object_size+0x24/0x30 
[  980.393774]  filldir64+0x548/0x84c 
[  980.397165]  xfs_dir2_block_getdents+0x404/0x960 [xfs] 
[  980.402437]  xfs_readdir+0x3c4/0x4b0 [xfs] 
[  980.406652]  xfs_file_readdir+0x6c/0xa0 [xfs] 
[  980.411127]  iterate_dir+0x3a4/0x500 
[  980.414691]  __do_sys_getdents64+0xb0/0x230 
[  980.418863]  __arm64_sys_getdents64+0x70/0xa0 
[  980.423209]  invoke_syscall.constprop.0+0xd8/0x1d0 
[  980.427991]  el0_svc_common.constprop.0+0x224/0x2bc 
[  980.432858]  do_el0_svc+0x4c/0x90 
[  980.436163]  el0_svc+0x5c/0x140 
[  980.439294]  el0t_64_sync_handler+0xb4/0x130 
[  980.443553]  el0t_64_sync+0x174/0x178 
[  980.447206] Code: f90003e3 aa0003e3 91098100 97ffe24b (d4210000)  
[  980.453292] SMP: stopping secondary CPUs 
[  980.458162] Starting crashdump kernel... 
[  980.462073] Bye!

> 
> Thanks!
>

On Sun, Jun 12, 2022 at 12:42:30PM +0800, Zorro Lang wrote:
> Looks likt it's not a s390x specific bug, I just hit this issue once (not
> 100%
> reproducible) on aarch64 with linux v5.19.0-rc1+ [1]. So back to cc linux-mm
> to get more review.
> 
> [1]
> [  980.200947] usercopy: Kernel memory exposure attempt detected from vmalloc
> 'no area' (offset 0, size 1)! 

       if (is_vmalloc_addr(ptr)) {
               struct vm_struct *area = find_vm_area(ptr);
               if (!area) {
                       usercopy_abort("vmalloc", "no area", to_user, 0, n);

Oh.  Looks like XFS uses vm_map_ram() and vm_map_ram() doesn't allocate
a vm_struct.

Ulad, how does this look to you?

diff --git a/mm/usercopy.c b/mm/usercopy.c
index baeacc735b83..6bc2a1407c59 100644
--- a/mm/usercopy.c
+++ b/mm/usercopy.c
@@ -173,7 +173,7 @@ static inline void check_heap_object(const void *ptr, unsigned long n,
 	}
 
 	if (is_vmalloc_addr(ptr)) {
-		struct vm_struct *area = find_vm_area(ptr);
+		struct vmap_area *area = find_vmap_area((unsigned long)ptr);
 		unsigned long offset;
 
 		if (!area) {
@@ -181,8 +181,9 @@ static inline void check_heap_object(const void *ptr, unsigned long n,
 			return;
 		}
 
-		offset = ptr - area->addr;
-		if (offset + n > get_vm_area_size(area))
+		/* XXX: We should also abort for free vmap_areas */
+		offset = (unsigned long)ptr - area->va_start;
+		if (offset + n >= area->va_end)
 			usercopy_abort("vmalloc", NULL, to_user, offset, n);
 		return;
 	}
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 07db42455dd4..effd1ff6a4b4 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1798,7 +1798,7 @@ static void free_unmap_vmap_area(struct vmap_area *va)
 	free_vmap_area_noflush(va);
 }
 
-static struct vmap_area *find_vmap_area(unsigned long addr)
+struct vmap_area *find_vmap_area(unsigned long addr)
 {
 	struct vmap_area *va;
 

> [  980.200968] ------------[ cut here ]------------ 
> [  980.200969] kernel BUG at mm/usercopy.c:101! 
> [  980.201081] Internal error: Oops - BUG: 0 [#1] SMP 
> [  980.224192] Modules linked in: rfkill arm_spe_pmu mlx5_ib ast
> drm_vram_helper drm_ttm_helper ttm ib_uverbs acpi_ipmi drm_kms_helper
> ipmi_ssif fb_sys_fops syscopyarea sysfillrect ib_core sysimgblt arm_cmn
> arm_dmc620_pmu arm_dsu_pmu cppc_cpufreq sunrpc vfat fat drm fuse xfs
> libcrc32c mlx5_core crct10dif_ce ghash_ce sha2_ce sha256_arm64 sha1_ce
> sbsa_gwdt nvme igb mlxfw nvme_core tls i2c_algo_bit psample pci_hyperv_intf
> i2c_designware_platform i2c_designware_core xgene_hwmon ipmi_devintf
> ipmi_msghandler 
> [  980.268449] CPU: 42 PID: 121940 Comm: rm Kdump: loaded Not tainted
> 5.19.0-rc1+ #1 
> [  980.275921] Hardware name: GIGABYTE R272-P30-JG/MP32-AR0-JG, BIOS F16f
> (SCP: 1.06.20210615) 07/01/2021 
> [  980.285214] pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS
> BTYPE=--) 
> [  980.292165] pc : usercopy_abort+0x78/0x7c 
> [  980.296167] lr : usercopy_abort+0x78/0x7c 
> [  980.300166] sp : ffff80002b007730 
> [  980.303469] x29: ffff80002b007740 x28: ffff80002b007cc0 x27:
> ffffdc5683ecc880 
> [  980.310595] x26: 1ffff00005600f9b x25: ffffdc5681c90000 x24:
> ffff80002b007cdc 
> [  980.317722] x23: ffff800041a0004a x22: 0000000000000001 x21:
> 0000000000000001 
> [  980.324848] x20: 0000000000000000 x19: ffff800041a00049 x18:
> 0000000000000000 
> [  980.331974] x17: 2720636f6c6c616d x16: 76206d6f72662064 x15:
> 6574636574656420 
> [  980.339101] x14: 74706d6574746120 x13: 21293120657a6973 x12:
> ffff6106cbc4c03f 
> [  980.346227] x11: 1fffe106cbc4c03e x10: ffff6106cbc4c03e x9 :
> ffffdc5681f36e30 
> [  980.353353] x8 : ffff08365e2601f7 x7 : 0000000000000001 x6 :
> ffff6106cbc4c03e 
> [  980.360480] x5 : ffff08365e2601f0 x4 : 1fffe10044b11801 x3 :
> 0000000000000000 
> [  980.367606] x2 : 0000000000000000 x1 : ffff08022588c000 x0 :
> 000000000000005c 
> [  980.374733] Call trace: 
> [  980.377167]  usercopy_abort+0x78/0x7c 
> [  980.380819]  check_heap_object+0x3dc/0x3e0 
> [  980.384907]  __check_object_size.part.0+0x6c/0x1f0 
> [  980.389688]  __check_object_size+0x24/0x30 
> [  980.393774]  filldir64+0x548/0x84c 
> [  980.397165]  xfs_dir2_block_getdents+0x404/0x960 [xfs] 
> [  980.402437]  xfs_readdir+0x3c4/0x4b0 [xfs] 
> [  980.406652]  xfs_file_readdir+0x6c/0xa0 [xfs] 
> [  980.411127]  iterate_dir+0x3a4/0x500

> On Sun, Jun 12, 2022 at 12:42:30PM +0800, Zorro Lang wrote:
> > Looks likt it's not a s390x specific bug, I just hit this issue once (not
> 100%
> > reproducible) on aarch64 with linux v5.19.0-rc1+ [1]. So back to cc
> linux-mm
> > to get more review.
> > 
> > [1]
> > [  980.200947] usercopy: Kernel memory exposure attempt detected from
> vmalloc 'no area' (offset 0, size 1)! 
> 
>        if (is_vmalloc_addr(ptr)) {
>                struct vm_struct *area = find_vm_area(ptr);
>                if (!area) {
>                        usercopy_abort("vmalloc", "no area", to_user, 0, n);
> 
> Oh.  Looks like XFS uses vm_map_ram() and vm_map_ram() doesn't allocate
> a vm_struct.
> 
> Ulad, how does this look to you?
>
It looks like a correct way to me :) XFS uses per-cpu-vm_map_ram()-vm_unmap_ram()
API which do not allocate "vm_struct" because it is not needed.

>
> diff --git a/mm/usercopy.c b/mm/usercopy.c
> index baeacc735b83..6bc2a1407c59 100644
> --- a/mm/usercopy.c
> +++ b/mm/usercopy.c
> @@ -173,7 +173,7 @@ static inline void check_heap_object(const void *ptr,
> unsigned long n,
>       }
>  
>       if (is_vmalloc_addr(ptr)) {
> -             struct vm_struct *area = find_vm_area(ptr);
> +             struct vmap_area *area = find_vmap_area((unsigned long)ptr);
>               unsigned long offset;
>  
>               if (!area) {
> @@ -181,8 +181,9 @@ static inline void check_heap_object(const void *ptr,
> unsigned long n,
>                       return;
>               }
>  
> -             offset = ptr - area->addr;
> -             if (offset + n > get_vm_area_size(area))
> +             /* XXX: We should also abort for free vmap_areas */
> +             offset = (unsigned long)ptr - area->va_start;
>
I was a bit confused about "offset" and why it is needed here. It is always zero. 
So we can get rid of it to make it less confused. From the other hand a zero offset
contributes to nothing.

>
> +             if (offset + n >= area->va_end)
>
I think it is a bit wrong. As i see it, "n" is a size and what we would like to do
here is boundary check:

<snip>
if (n > va_size(area))
    usercopy_abort("vmalloc", NULL, to_user, 0, n);
<snip>

--
Uladzislau Rezki

On Sun, Jun 12, 2022 at 03:03:20PM +0200, Uladzislau Rezki wrote:
> > @@ -181,8 +181,9 @@ static inline void check_heap_object(const void *ptr,
> unsigned long n,
> >                     return;
> >             }
> >  
> > -           offset = ptr - area->addr;
> > -           if (offset + n > get_vm_area_size(area))
> > +           /* XXX: We should also abort for free vmap_areas */
> > +           offset = (unsigned long)ptr - area->va_start;
> >
> I was a bit confused about "offset" and why it is needed here. It is always
> zero. 
> So we can get rid of it to make it less confused. From the other hand a zero
> offset
> contributes to nothing.

I don't think offset is necessarily zero.  'ptr' is a pointer somewhere
in the object, not necessarily the start of the object.

> >
> > +           if (offset + n >= area->va_end)
> >
> I think it is a bit wrong. As i see it, "n" is a size and what we would like
> to do
> here is boundary check:
> 
> <snip>
> if (n > va_size(area))
>     usercopy_abort("vmalloc", NULL, to_user, 0, n);
> <snip>

Hmm ... we should probably be more careful about wrapping.

                if (n > area->va_end - addr)
                        usercopy_abort("vmalloc", NULL, to_user, offset, n);

... and that goes for the whole function actually.  I'll split that into
a separate change.

On Sun, Jun 12, 2022 at 11:27 AM Matthew Wilcox <willy@infradead.org> wrote:
>
> On Sun, Jun 12, 2022 at 03:03:20PM +0200, Uladzislau Rezki wrote:
> > > @@ -181,8 +181,9 @@ static inline void check_heap_object(const void *ptr,
> unsigned long n,
> > >                     return;
> > >             }
> > >
> > > -           offset = ptr - area->addr;
> > > -           if (offset + n > get_vm_area_size(area))
> > > +           /* XXX: We should also abort for free vmap_areas */
> > > +           offset = (unsigned long)ptr - area->va_start;
> > >
> > I was a bit confused about "offset" and why it is needed here. It is always
> zero.
> > So we can get rid of it to make it less confused. From the other hand a
> zero offset
> > contributes to nothing.
>
> I don't think offset is necessarily zero.  'ptr' is a pointer somewhere
> in the object, not necessarily the start of the object.
>
> > >
> > > +           if (offset + n >= area->va_end)
> > >
> > I think it is a bit wrong. As i see it, "n" is a size and what we would
> like to do
> > here is boundary check:
> >
> > <snip>
> > if (n > va_size(area))
> >     usercopy_abort("vmalloc", NULL, to_user, 0, n);
> > <snip>
>
> Hmm ... we should probably be more careful about wrapping.
>
>                 if (n > area->va_end - addr)
>                         usercopy_abort("vmalloc", NULL, to_user, offset, n);
>
> ... and that goes for the whole function actually.  I'll split that into
> a separate change.

Please let me know if there is something we want to test -- I can
reproduce the problem reliably:

------------[ cut here ]------------
kernel BUG at mm/usercopy.c:101!
Internal error: Oops - BUG: 0 [#1] PREEMPT SMP
CPU: 4 PID: 3259 Comm: iptables Not tainted 5.19.0-rc1-lockdep+ #1
pc : usercopy_abort+0x9c/0xa0
lr : usercopy_abort+0x9c/0xa0
sp : ffffffc010bd78d0
x29: ffffffc010bd78e0 x28: 42ffff80ac08d8ec x27: 42ffff80ac08d8ec
x26: 42ffff80ac08d8c0 x25: 000000000000000a x24: ffffffdf4c7e5120
x23: 000000000bec44c2 x22: efffffc000000000 x21: ffffffdf2896b0c0
x20: 0000000000000001 x19: 000000000000000b x18: 0000000000000000
x17: 2820636f6c6c616d x16: 0000000000000042 x15: 6574636574656420
x14: 74706d6574746120 x13: 0000000000000018 x12: 000000000000000d
x11: ff80007fffffffff x10: 0000000000000001 x9 : db174b7f89103400
x8 : db174b7f89103400 x7 : 0000000000000000 x6 : 79706f6372657375
x5 : ffffffdf4d9c617e x4 : 0000000000000000 x3 : ffffffdf4b7d017c
x2 : ffffff80eb188b18 x1 : 42ffff80ac08d8c8 x0 : 0000000000000066
Call trace:
 usercopy_abort+0x9c/0xa0
 __check_object_size+0x38c/0x400
 xt_obj_to_user+0xe4/0x200
 xt_compat_target_to_user+0xd8/0x18c
 compat_copy_entries_to_user+0x278/0x424
 do_ipt_get_ctl+0x7bc/0xb2c
 nf_getsockopt+0x7c/0xb4
 ip_getsockopt+0xee8/0xfa4
 raw_getsockopt+0xf4/0x23c
 sock_common_getsockopt+0x48/0x54
 __sys_getsockopt+0x11c/0x2f8
 __arm64_sys_getsockopt+0x60/0x70
 el0_svc_common+0xfc/0x1cc
 do_el0_svc_compat+0x38/0x5c
 el0_svc_compat+0x68/0xf4
 el0t_32_sync_handler+0xc0/0xf0
 el0t_32_sync+0x190/0x194
Code: aa0903e4 a9017bfd 910043fd 9438be18 (d4210000)
---[ end trace 0000000000000000 ]---

On Sun, Jun 12, 2022 at 11:59:58AM -0600, Yu Zhao wrote:
> Please let me know if there is something we want to test -- I can
> reproduce the problem reliably:
> 
> ------------[ cut here ]------------
> kernel BUG at mm/usercopy.c:101!

The line right before cut here would have been nice ;-)

https://lore.kernel.org/linux-mm/YqXU+oU7wayOcmCe@casper.infradead.org/

might fix your problem, but I can't be sure without that line.

> Internal error: Oops - BUG: 0 [#1] PREEMPT SMP
> CPU: 4 PID: 3259 Comm: iptables Not tainted 5.19.0-rc1-lockdep+ #1
> pc : usercopy_abort+0x9c/0xa0
> lr : usercopy_abort+0x9c/0xa0
> sp : ffffffc010bd78d0
> x29: ffffffc010bd78e0 x28: 42ffff80ac08d8ec x27: 42ffff80ac08d8ec
> x26: 42ffff80ac08d8c0 x25: 000000000000000a x24: ffffffdf4c7e5120
> x23: 000000000bec44c2 x22: efffffc000000000 x21: ffffffdf2896b0c0
> x20: 0000000000000001 x19: 000000000000000b x18: 0000000000000000
> x17: 2820636f6c6c616d x16: 0000000000000042 x15: 6574636574656420
> x14: 74706d6574746120 x13: 0000000000000018 x12: 000000000000000d
> x11: ff80007fffffffff x10: 0000000000000001 x9 : db174b7f89103400
> x8 : db174b7f89103400 x7 : 0000000000000000 x6 : 79706f6372657375
> x5 : ffffffdf4d9c617e x4 : 0000000000000000 x3 : ffffffdf4b7d017c
> x2 : ffffff80eb188b18 x1 : 42ffff80ac08d8c8 x0 : 0000000000000066
> Call trace:
>  usercopy_abort+0x9c/0xa0
>  __check_object_size+0x38c/0x400
>  xt_obj_to_user+0xe4/0x200
>  xt_compat_target_to_user+0xd8/0x18c
>  compat_copy_entries_to_user+0x278/0x424
>  do_ipt_get_ctl+0x7bc/0xb2c
>  nf_getsockopt+0x7c/0xb4
>  ip_getsockopt+0xee8/0xfa4
>  raw_getsockopt+0xf4/0x23c
>  sock_common_getsockopt+0x48/0x54
>  __sys_getsockopt+0x11c/0x2f8
>  __arm64_sys_getsockopt+0x60/0x70
>  el0_svc_common+0xfc/0x1cc
>  do_el0_svc_compat+0x38/0x5c
>  el0_svc_compat+0x68/0xf4
>  el0t_32_sync_handler+0xc0/0xf0
>  el0t_32_sync+0x190/0x194
> Code: aa0903e4 a9017bfd 910043fd 9438be18 (d4210000)
> ---[ end trace 0000000000000000 ]---

On Sun, Jun 12, 2022 at 12:05 PM Matthew Wilcox <willy@infradead.org> wrote:
>
> On Sun, Jun 12, 2022 at 11:59:58AM -0600, Yu Zhao wrote:
> > Please let me know if there is something we want to test -- I can
> > reproduce the problem reliably:
> >
> > ------------[ cut here ]------------
> > kernel BUG at mm/usercopy.c:101!
>
> The line right before cut here would have been nice ;-)

Right.

$ grep usercopy:
usercopy: Kernel memory exposure attempt detected from vmalloc (offset
2882303761517129920, size 11)!
usercopy: Kernel memory exposure attempt detected from vmalloc (offset
8574853690513436864, size 11)!
usercopy: Kernel memory exposure attempt detected from vmalloc (offset
7998392938210013376, size 11)!
...

> https://lore.kernel.org/linux-mm/YqXU+oU7wayOcmCe@casper.infradead.org/
>
> might fix your problem, but I can't be sure without that line.

Thanks, it worked!

> On Sun, Jun 12, 2022 at 03:03:20PM +0200, Uladzislau Rezki wrote:
> > > @@ -181,8 +181,9 @@ static inline void check_heap_object(const void *ptr,
> unsigned long n,
> > >                   return;
> > >           }
> > >  
> > > -         offset = ptr - area->addr;
> > > -         if (offset + n > get_vm_area_size(area))
> > > +         /* XXX: We should also abort for free vmap_areas */
> > > +         offset = (unsigned long)ptr - area->va_start;
> > >
> > I was a bit confused about "offset" and why it is needed here. It is always
> zero. 
> > So we can get rid of it to make it less confused. From the other hand a
> zero offset
> > contributes to nothing.
> 
> I don't think offset is necessarily zero.  'ptr' is a pointer somewhere
> in the object, not necessarily the start of the object.
> 
Right you are. Just checked the __find_vmap_area() it returns VA of the address it
belongs to. Initially i was thinking that addr have to be exactly as va->start only,
so i was wrong.

> > >
> > > +         if (offset + n >= area->va_end)
> > >
> > I think it is a bit wrong. As i see it, "n" is a size and what we would
> like to do
> > here is boundary check:
> > 
> > <snip>
> > if (n > va_size(area))
> >     usercopy_abort("vmalloc", NULL, to_user, 0, n);
> > <snip>
> 
> Hmm ... we should probably be more careful about wrapping.
> 
>                 if (n > area->va_end - addr)
>                         usercopy_abort("vmalloc", NULL, to_user, offset, n);
> 
> ... and that goes for the whole function actually.  I'll split that into
> a separate change.
> 
Based on that offset can be > 0, checking "offset + n" with va->va_end is OK.

<snip>
if (offset + n > area->va_end)
    usercopy_abort("vmalloc", NULL, to_user, offset, n);
<snip>

--
Uladzislau Rezki

On Sun, Jun 12, 2022 at 12:43:45PM -0600, Yu Zhao wrote:
> On Sun, Jun 12, 2022 at 12:05 PM Matthew Wilcox <willy@infradead.org> wrote:
> >
> > On Sun, Jun 12, 2022 at 11:59:58AM -0600, Yu Zhao wrote:
> > > Please let me know if there is something we want to test -- I can
> > > reproduce the problem reliably:
> > >
> > > ------------[ cut here ]------------
> > > kernel BUG at mm/usercopy.c:101!
> >
> > The line right before cut here would have been nice ;-)
> 
> Right.
> 
> $ grep usercopy:
> usercopy: Kernel memory exposure attempt detected from vmalloc (offset
> 2882303761517129920, size 11)!
> usercopy: Kernel memory exposure attempt detected from vmalloc (offset
> 8574853690513436864, size 11)!
> usercopy: Kernel memory exposure attempt detected from vmalloc (offset
> 7998392938210013376, size 11)!

That's a different problem.  And, er, what?  How on earth do we have
an offset that big?!

                struct vm_struct *area = find_vm_area(ptr);
                offset = ptr - area->addr;
                if (offset + n > get_vm_area_size(area))
                        usercopy_abort("vmalloc", NULL, to_user, offset, n);

That first offset is 0x2800'0000'0000'30C0

You said it was easy to replicate; can you add:

			printk("addr:%px ptr:%px\n", area->addr, ptr);

so that we can start to understand how we end up with such a bogus
offset?

On Sun, Jun 12, 2022 at 1:52 PM Matthew Wilcox <willy@infradead.org> wrote:
>
> On Sun, Jun 12, 2022 at 12:43:45PM -0600, Yu Zhao wrote:
> > On Sun, Jun 12, 2022 at 12:05 PM Matthew Wilcox <willy@infradead.org>
> wrote:
> > >
> > > On Sun, Jun 12, 2022 at 11:59:58AM -0600, Yu Zhao wrote:
> > > > Please let me know if there is something we want to test -- I can
> > > > reproduce the problem reliably:
> > > >
> > > > ------------[ cut here ]------------
> > > > kernel BUG at mm/usercopy.c:101!
> > >
> > > The line right before cut here would have been nice ;-)
> >
> > Right.
> >
> > $ grep usercopy:
> > usercopy: Kernel memory exposure attempt detected from vmalloc (offset
> > 2882303761517129920, size 11)!
> > usercopy: Kernel memory exposure attempt detected from vmalloc (offset
> > 8574853690513436864, size 11)!
> > usercopy: Kernel memory exposure attempt detected from vmalloc (offset
> > 7998392938210013376, size 11)!
>
> That's a different problem.  And, er, what?  How on earth do we have
> an offset that big?!
>
>                 struct vm_struct *area = find_vm_area(ptr);
>                 offset = ptr - area->addr;
>                 if (offset + n > get_vm_area_size(area))
>                         usercopy_abort("vmalloc", NULL, to_user, offset, n);
>
> That first offset is 0x2800'0000'0000'30C0
>
> You said it was easy to replicate; can you add:
>
>                         printk("addr:%px ptr:%px\n", area->addr, ptr);
>
> so that we can start to understand how we end up with such a bogus
> offset?

Here you go:

addr:96ffffdfebcd4000 ptr:ffffffdfebcd70c0
usercopy: Kernel memory exposure attempt detected from vmalloc (offset
7566047373982445760, size 11)!

And, not sure if it'd be helpful, with the vmap:

va_start:ffffffd83db0d000 va_end:ffffffd83db13000
addr:44ffffd83db0d000 ptr:ffffffd83db100c0
usercopy: Kernel memory exposure attempt detected from vmalloc (offset
13474770085092536512, size 11)!

which seems to explain why the fix worked.

+               if (offset + n > get_vm_area_size(area)) {
+                       struct vmap_area *vmap =
find_vmap_area((unsigned long)ptr);
+
+                       if (vmap)
+                               printk("va_start:%px va_end:%px\n",
vmap->va_start, vmap->va_end);
+                       printk("addr:%px ptr:%px\n", area->addr, ptr);
                        usercopy_abort("vmalloc", NULL, to_user, offset, n);
+               }