From: Thomas Gleixner <tglx@linutronix.de>
To: syzbot <syzbot+7ffc7214b893651d52b8@syzkaller.appspotmail.com>,
keescook@chromium.org, linux-kernel@vger.kernel.org,
mingo@kernel.org, syzkaller-bugs@googlegroups.com,
Christian Brauner <christian@brauner.io>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: WARNING in syscall_exit_to_user_mode
Date: Sun, 13 Sep 2020 21:40:14 +0200 [thread overview]
Message-ID: <87y2ldpish.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <00000000000018a47605af074c7d@google.com>
On Fri, Sep 11 2020 at 03:39, syzbot wrote:
>
> ------------[ cut here ]------------
> syscall 56 left IRQs disabled
Ouch. syscall 56 == sys_clone
> WARNING: CPU: 1 PID: 31467 at kernel/entry/common.c:245 syscall_exit_to_user_mode_prepare kernel/entry/common.c:245 [inline]
<snip>
> ret_from_fork+0x15/0x30 arch/x86/entry/entry_64.S:287
But this does not make any sense for regular fork because
ret_from_fork() invokes schedule_tail() which drops the runqueue lock
and enables interrupts.
But for kernel threads that's more interesting because after
schedule_tail() the kernel thread function is invoked and this can call
kernel_execve() and return to ret_from_fork() and then run through
syscall_exit_to_user_mode().
Let me get that reproducer...
next prev parent reply other threads:[~2020-09-13 19:40 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-11 10:39 WARNING in syscall_exit_to_user_mode syzbot
2020-09-12 17:52 ` Kees Cook
2020-09-13 19:54 ` Thomas Gleixner
2020-09-14 20:06 ` Kees Cook
2020-09-14 20:22 ` Thomas Gleixner
2020-09-13 19:40 ` Thomas Gleixner [this message]
2020-11-08 17:22 ` syzbot
2020-11-11 11:11 ` Dmitry Vyukov
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