From: ebiederm@xmission.com (Eric W. Biederman)
To: syzbot <syzbot+b80bbdcca4c4dfaa189e@syzkaller.appspotmail.com>
Cc: akpm@linux-foundation.org, ast@kernel.org, christian@brauner.io,
jnewsome@torproject.org, linux-kernel@vger.kernel.org,
minchan@kernel.org, oleg@redhat.com,
syzkaller-bugs@googlegroups.com, Ingo Molnar <mingo@kernel.org>
Subject: Re: [syzbot] KASAN: out-of-bounds Read in do_exit
Date: Thu, 24 Jun 2021 00:30:16 -0500 [thread overview]
Message-ID: <87fsx7akyf.fsf@disp2133> (raw)
In-Reply-To: <000000000000ef5d1b05c57c2262@google.com> (syzbot's message of "Wed, 23 Jun 2021 22:17:16 -0700")
syzbot <syzbot+b80bbdcca4c4dfaa189e@syzkaller.appspotmail.com> writes:
> Hello,
>
> syzbot found the following issue on:
This looks like dueling debug mechanism. At a quick glance
stack_no_used is deliberately looking for an uninitialized part of the
stack.
Perhaps the fix is to make KASAN and DEBUG_STACK_USAGE impossible to
select at the same time in Kconfig?
Eric
>
> HEAD commit: 9ed13a17 Merge tag 'net-5.13-rc7' of git://git.kernel.org/..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=116c517bd00000
> kernel config: https://syzkaller.appspot.com/x/.config?x=bf635d6d1c7ebabc
> dashboard link: https://syzkaller.appspot.com/bug?extid=b80bbdcca4c4dfaa189e
> compiler: Debian clang version 11.0.1-2
>
> Unfortunately, I don't have any reproducer for this issue yet.
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+b80bbdcca4c4dfaa189e@syzkaller.appspotmail.com
>
> ==================================================================
> BUG: KASAN: out-of-bounds in stack_not_used include/linux/sched/task_stack.h:101 [inline]
> BUG: KASAN: out-of-bounds in check_stack_usage kernel/exit.c:711 [inline]
> BUG: KASAN: out-of-bounds in do_exit+0x1c6b/0x23d0 kernel/exit.c:869
> Read of size 8 at addr ffffc90017d60400 by task loop0/31717
>
> CPU: 0 PID: 31717 Comm: loop0 Not tainted 5.13.0-rc6-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> Call Trace:
> __dump_stack lib/dump_stack.c:79 [inline]
> dump_stack+0x202/0x31e lib/dump_stack.c:120
> print_address_description+0x5f/0x3b0 mm/kasan/report.c:233
> __kasan_report mm/kasan/report.c:419 [inline]
> kasan_report+0x15c/0x200 mm/kasan/report.c:436
> stack_not_used include/linux/sched/task_stack.h:101 [inline]
> check_stack_usage kernel/exit.c:711 [inline]
> do_exit+0x1c6b/0x23d0 kernel/exit.c:869
> kthread+0x3b8/0x3c0 kernel/kthread.c:315
> ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
>
>
> Memory state around the buggy address:
> ffffc90017d60300: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> ffffc90017d60380: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>>ffffc90017d60400: 07 07 07 07 07 07 07 07 00 00 00 00 00 00 00 00
> ^
> ffffc90017d60480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> ffffc90017d60500: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> ==================================================================
>
>
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@googlegroups.com.
>
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
next prev parent reply other threads:[~2021-06-24 5:31 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-24 5:17 [syzbot] KASAN: out-of-bounds Read in do_exit syzbot
2021-06-24 5:30 ` Eric W. Biederman [this message]
2021-06-25 14:39 ` Dmitry Vyukov
2021-06-25 18:59 ` Eric W. Biederman
2021-06-26 5:17 ` Dmitry Vyukov
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