From: Christian Brauner <christian.brauner@ubuntu.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: syzbot <syzbot+0bac5fec63d4f399ba98@syzkaller.appspotmail.com>,
axboe@kernel.dk, christian@brauner.io, ebiederm@xmission.com,
elver@google.com, linux-kernel@vger.kernel.org, oleg@redhat.com,
pcc@google.com, peterz@infradead.org,
syzkaller-bugs@googlegroups.com
Subject: Re: [PATCH] signal: Prevent sigqueue caching after task got released
Date: Tue, 22 Jun 2021 10:06:39 +0200 [thread overview]
Message-ID: <20210622080639.nk5buzset4ucchnk@wittgenstein> (raw)
In-Reply-To: <878s32g6j5.ffs@nanos.tec.linutronix.de>
On Tue, Jun 22, 2021 at 01:08:30AM +0200, Thomas Gleixner wrote:
> syzbot reported a memory leak related to sigqueue caching. This happens
> when a thread group leader with child tasks is reaped.
>
> The group leader's sigqueue_cache is correctly freed. The group leader then
> reaps the child tasks and if any of them has a signal pending it caches
> that signal. That's obviously bogus because nothing will free the cached
> signal of the reaped group leader anymore.
>
> Prevent this by setting tsk::sigqueue_cache to an error pointer value in
> exit_task_sigqueue_cache().
>
> Add comments to all relevant places.
>
> Fixes: 4bad58ebc8bc ("signal: Allow tasks to cache one sigqueue struct")
> Reported-by: syzbot+0bac5fec63d4f399ba98@syzkaller.appspotmail.com
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> ---
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
next prev parent reply other threads:[~2021-06-22 8:06 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-06 14:32 [syzbot] memory leak in __send_signal syzbot
2021-06-21 23:08 ` [PATCH] signal: Prevent sigqueue caching after task got released Thomas Gleixner
2021-06-22 6:34 ` Oleg Nesterov
2021-06-22 7:59 ` Thomas Gleixner
2021-06-22 8:06 ` Christian Brauner [this message]
2021-06-22 13:59 ` [tip: core/urgent] " tip-bot2 for Thomas Gleixner
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