Created attachment 295545 [details] poc C file Hello, I found a bug in kernel version 5.11.0-rc7+. This is the POC. 1.Git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 2.Build kernel with CONFIG_KASAN 3.Run kernel with qemu ``` qemu-system-x86_64 \ -m 1G \ -smp 2 \ -kernel bzImage \ -append "console=ttyS0 root=/dev/sda earlyprintk=serial net.ifnames=0" \ -drive file=stretch.img,format=raw \ -net user,host=10.0.2.10,hostfwd=tcp:127.0.0.1:1569-:22 \ -net nic,model=e1000 \ -nographic \ -enable-kvm ``` 4.Compile POC and scp into qemu. ``` gcc tcp_recvmsg_locked.c -static -lpthread scp -P 1569 a.out root@localhost:~ ``` 5.Run a.out you will see the dump log. ``` root@syzkaller:~# ./a.out [ 111.196095] audit: type=1400 audit(1614585907.556:8): avc: denied { execmem } for pid=356 comm="a.out" scontext=system_u:system_r:kernel_t:s0 tcontext=system_u:system_r:kernel_t:s0 tclass=process permissive=1 [ 111.203295] ------------[ cut here ]------------ [ 111.205099] TCP recvmsg seq # bug 2: copied 80, seq 0, rcvnxt 80, fl 0 [ 111.207894] WARNING: CPU: 1 PID: 356 at net/ipv4/tcp.c:2343 tcp_recvmsg_locked+0x90e/0x29a0 [ 111.212756] Modules linked in: [ 111.214115] CPU: 1 PID: 356 Comm: a.out Not tainted 5.11.0-rc7+ #1 [ 111.216911] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014 [ 111.220464] RIP: 0010:tcp_recvmsg_locked+0x90e/0x29a0 [ 111.222596] Code: 48 c1 e8 03 0f b6 04 18 84 c0 0f 85 18 01 00 00 8b 0a 48 c7 c7 60 04 d0 86 44 89 fe 89 ea 44 8b 44 24 2c 31 c0 e8 32 3d c3 fd <0f> 0b e9 2e ff ff ff e8 76 f2 eb fd c6 05 29 7d bf 01 01 48 c7 c7 [ 111.228525] RSP: 0018:ffff888001a4fab8 EFLAGS: 00010246 [ 111.229905] RAX: f2b8163648339800 RBX: dffffc0000000000 RCX: ffff8880035b9c00 [ 111.232193] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 [ 111.234829] RBP: 0000000000000000 R08: ffffffff83928cd0 R09: ffffed10061a5d1a [ 111.236645] R10: ffffed10061a5d1a R11: 0000000000000000 R12: 00000000ffffff94 [ 111.238287] R13: ffff888001ed0b68 R14: 1ffff110003da16d R15: 0000000000000080 [ 111.239721] FS: 00000000010da880(0000) GS:ffff888030d00000(0000) knlGS:0000000000000000 [ 111.241303] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 111.242461] CR2: 00000000004608dd CR3: 0000000003948000 CR4: 00000000000006e0 [ 111.243806] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 111.245072] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 111.246337] Call Trace: [ 111.246775] tcp_recvmsg+0x1c9/0xd50 [ 111.247397] ? memset+0x1f/0x40 [ 111.247978] ? selinux_socket_recvmsg+0xaf/0x240 [ 111.248820] ? tcp_v6_do_rcv+0x542/0x1280 [ 111.249415] ? tcp_mmap+0xc0/0xc0 [ 111.249966] inet6_recvmsg+0x107/0x480 [ 111.250509] ? inet6_sendmsg+0x120/0x120 [ 111.251101] __sys_recvfrom+0x34d/0x530 [ 111.251695] ? do_tcp_setsockopt+0x2381/0x33d0 [ 111.252447] ? tcp_setsockopt+0x3a/0xf0 [ 111.253339] ? __sys_setsockopt+0x1fd/0x270 [ 111.254743] ? sock_common_recvmsg+0x190/0x190 [ 111.256106] ? __sys_setsockopt+0x211/0x270 [ 111.256693] __x64_sys_recvfrom+0xda/0xf0 [ 111.257430] do_syscall_64+0x33/0x40 [ 111.258145] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 111.259133] RIP: 0033:0x449cb9 [ 111.259646] Code: 00 b8 00 01 00 00 eb e1 e8 f4 19 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48 [ 111.262498] RSP: 002b:00007fffaa2b0328 EFLAGS: 00000212 ORIG_RAX: 000000000000002d [ 111.263615] RAX: ffffffffffffffda RBX: 0000000020000050 RCX: 0000000000449cb9 [ 111.264686] RDX: 0000000000000014 RSI: 0000000000000000 RDI: 0000000000000003 [ 111.265573] RBP: 00007fffaa2b0360 R08: 0000000000000000 R09: 0000000000000000 [ 111.266342] R10: 0000000000000000 R11: 0000000000000212 R12: 0000000000401cb0 [ 111.267090] R13: 0000000000000000 R14: 00000000006b9018 R15: 0000000000000000 [ 111.267838] ---[ end trace 3bc6b032cf6c31f5 ]--- [ 111.268332] ------------[ cut here ]------------ [ 111.268873] cleanup rbuf bug: copied 80 seq 14 rcvnxt 80 [ 111.269477] WARNING: CPU: 1 PID: 356 at net/ipv4/tcp.c:1555 tcp_cleanup_rbuf+0x3f4/0x5a0 [ 111.270330] Modules linked in: [ 111.270655] CPU: 1 PID: 356 Comm: a.out Tainted: G W 5.11.0-rc7+ #1 [ 111.271445] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014 [ 111.272370] RIP: 0010:tcp_cleanup_rbuf+0x3f4/0x5a0 [ 111.272886] Code: b9 00 00 00 00 00 fc ff df 8a 04 08 84 c0 0f 85 9a 01 00 00 41 8b 0c 24 48 c7 c7 60 ff cf 86 89 ee 89 da 31 c0 e8 0c 70 c3 fd <0f> 0b e9 a5 fc ff ff 44 89 e9 80 e1 07 38 c1 0f 8c bb fc ff ff 4c [ 111.274834] RSP: 0018:ffff888001a4fa78 EFLAGS: 00010246 [ 111.275404] RAX: f2b8163648339800 RBX: 0000000000000014 RCX: ffff8880035b9c00 [ 111.276148] RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 [ 111.276890] RBP: 0000000000000080 R08: ffffffff83a84a02 R09: ffffed10061a3f23 [ 111.277702] R10: ffffed10061a3f23 R11: 0000000000000000 R12: ffff8880075e0570 [ 111.278560] R13: ffff888001ed0b68 R14: 00000000ffffff98 R15: ffff8880075e0000 [ 111.279307] FS: 00000000010da880(0000) GS:ffff888030d00000(0000) knlGS:0000000000000000 [ 111.280261] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 111.280866] CR2: 00000000004608dd CR3: 0000000003948000 CR4: 00000000000006e0 [ 111.281594] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 111.282495] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 111.283815] Call Trace: [ 111.284275] tcp_recvmsg_locked+0x2206/0x29a0 [ 111.285467] tcp_recvmsg+0x1c9/0xd50 [ 111.285979] ? memset+0x1f/0x40 [ 111.286394] ? selinux_socket_recvmsg+0xaf/0x240 [ 111.286996] ? tcp_v6_do_rcv+0x542/0x1280 [ 111.287431] ? tcp_mmap+0xc0/0xc0 [ 111.287895] inet6_recvmsg+0x107/0x480 [ 111.288313] ? inet6_sendmsg+0x120/0x120 [ 111.288888] __sys_recvfrom+0x34d/0x530 [ 111.289391] ? do_tcp_setsockopt+0x2381/0x33d0 [ 111.289954] ? tcp_setsockopt+0x3a/0xf0 [ 111.290429] ? __sys_setsockopt+0x1fd/0x270 [ 111.290942] ? sock_common_recvmsg+0x190/0x190 [ 111.291416] ? __sys_setsockopt+0x211/0x270 [ 111.291871] __x64_sys_recvfrom+0xda/0xf0 [ 111.292323] do_syscall_64+0x33/0x40 [ 111.292700] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 111.293240] RIP: 0033:0x449cb9 [ 111.293567] Code: 00 b8 00 01 00 00 eb e1 e8 f4 19 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48 [ 111.295468] RSP: 002b:00007fffaa2b0328 EFLAGS: 00000212 ORIG_RAX: 000000000000002d [ 111.296323] RAX: ffffffffffffffda RBX: 0000000020000050 RCX: 0000000000449cb9 [ 111.297142] RDX: 0000000000000014 RSI: 0000000000000000 RDI: 0000000000000003 [ 111.298007] RBP: 00007fffaa2b0360 R08: 0000000000000000 R09: 0000000000000000 [ 111.298718] R10: 0000000000000000 R11: 0000000000000212 R12: 0000000000401cb0 [ 111.299475] R13: 0000000000000000 R14: 00000000006b9018 R15: 0000000000000000 [ 111.300202] ---[ end trace 3bc6b032cf6c31f6 ]--- ```
https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git/commit/?id=8811f4a9836e
Hello, Can I request a CVE number? Thanks.
Reported by Qingyu Li from Amber Lab, OPPO.