Messages in this thread | | | Date | Wed, 30 Mar 2022 21:46:11 +0300 | Subject | Re: [syzbot] KASAN: use-after-free Read in em28xx_init_extension (2) | From | Pavel Skripkin <> |
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On 3/30/22 20:36, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: 52d543b5497c Merge tag 'for-linus-5.17-1' of https://githu.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=17b804fb700000 > kernel config: https://syzkaller.appspot.com/x/.config?x=7094767cefc58fb9 > dashboard link: https://syzkaller.appspot.com/bug?extid=99d6c66dbbc484f50e1c > compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=161c4739700000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16432d51700000 > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+99d6c66dbbc484f50e1c@syzkaller.appspotmail.com > > em28xx 5-1:0.130: Config register raw data: 0xfffffffb > em28xx 5-1:0.130: AC97 chip type couldn't be determined > em28xx 5-1:0.130: No AC97 audio processor > ================================================================== > BUG: KASAN: use-after-free in __list_add_valid+0x93/0xa0 lib/list_debug.c:26 > Read of size 8 at addr ffff888027458250 by task kworker/1:1/40 >
Just want to warn anyone looking into this bug.
I came up with the fix, that passed syzbot testing and patch has been in Linus' tree for couple of months: see commit 2c98b8a3458d ("media: em28xx: add missing em28xx_close_extension").
After some time Maximilian sent a report about kernel hung bug caused by my fix [1]. Just random hung caused by wrong reference counting somewhere. No idea how to reproduce it locally or how to fix it.
I had to revert my fix, of course. That's why this bug appeared one more time.
So, if you are going to send a fix, please, check that it does not have same problem as mine.
Thanks
[1] https://lore.kernel.org/all/6a72a37b-e972-187d-0322-16336e12bdc5@elbmurf.de/
With regards, Pavel Skripkin
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