Bug 207703

Summary: kernel BUG at mm/slub.c:306!
Product: Networking Reporter: LI AR (sexxxenator)
Component: WirelessAssignee: Brian Norris (briannorris)
Status: RESOLVED PATCH_ALREADY_AVAILABLE    
Severity: high CC: briannorris, nadpher
Priority: P1    
Hardware: x86-64   
OS: Linux   
Kernel Version: 5.4.0-29-generic #33-Ubuntu SMP Tree: Mainline
Regression: Yes
Attachments: Crash due to bug in ath9k

Description LI AR 2020-05-12 15:21:57 UTC
Created attachment 289093 [details]
Crash due to bug in ath9k

Hi,

I've upgraded my XUbuntu to 20.04. Since then I've encountered several crashes.

Apparently, there's a bug in ath9k...

See attached kernel trace
Comment 1 Brian Norris 2020-05-12 16:50:40 UTC
I believe you're hitting a double-free in a kfree_skb() added by this commit, which first appeared in 5.4:

commit 728c1e2a05e4b5fc52fab3421dce772a806612a2
Author: Navid Emamdoost <navid.emamdoost@gmail.com>
Date:   Fri Sep 6 13:59:30 2019 -0500

    ath9k: release allocated buffer if timed out

It would seem that this patch is buggy and probably should be reverted. IIUC, we've already "submitted" the SKB to another layer at that point, and that layer should be responsible for freeing it (e.g., in hif_usb_regout_cb).

I wonder about the author's other patches, which all seem to be the same sort of mechanical (likely-untested) "leak-fixing" patches...
Comment 2 Brian Norris 2020-05-13 19:00:09 UTC
It looks like this is already reverted in linux-next:

commit ced21a4c726bdc60b1680c050a284b08803bc64c
Author: Qiujun Huang <hqjagain@gmail.com>
Date:   Sat Apr 4 12:18:34 2020 +0800

    ath9k: Fix use-after-free Read in htc_connect_service

https://git.kernel.org/pub/scm/linux/kernel/git/kvalo/wireless-drivers-next.git/commit/?id=ced21a4c726bdc60b1680c050a284b08803bc64c

It's on its way to 5.8:

https://lkml.kernel.org/linux-wireless/878shwtiw3.fsf@kamboji.qca.qualcomm.com/T/#t

If you have the ability to apply that patch to your own kernel, you might give it a try. Hopefully we can get it queued to -stable eventually.
Comment 3 Brian Norris 2020-05-20 20:56:58 UTC
*** Bug 207797 has been marked as a duplicate of this bug. ***
Comment 4 Brian Norris 2020-07-02 03:33:50 UTC
For the record, the patch was merged to v5.4.47 (and other newer kernels)