Messages in this thread | | | Date | Mon, 13 Feb 2023 12:27:55 +0800 | Subject | Re: [PATCH 0/1] autofs: fix memory leak of waitqueues in autofs_catatonic_mode | From | Ian Kent <> |
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On 12/2/23 03:59, Fedor Pchelkin wrote: > Syzkaller reports the leak [1]. It is reproducible. > > The following patch fixes the leak. It was proposed by Takeshi Misawa and > tested by Syzbot. > > In other places of the code the waitqueue is freed when its wait_ctr > becomes zero (see autofs_wait_release). So I think it is not actually > supposed that inside autofs_catatonic_mode wait_ctr cannot be decreased to > zero. Please correct me if I'm wrong.
This is a bit had to read but I think your saying there's an assumption
that wait_ctr can't become zero in autofs_catatonic_mode().
That's correct, the case of a waiting process getting sent a signal is
not accounted for and this can (as you observed) lead to the wait not
being freed and also not being freed at umount.
I think the change here should be sufficient to resolve the leak and
I can't think of any cases where this could cause a further problem.
> > Also, looking at the discussion [2] of the '[PATCH] autofs4: use wake_up() > instead of wake_up_interruptible', shouldn't wake_up_interruptible() > inside autofs_catatonic_mode() be replaced with wake_up()?
This does imply that [2] should have been applied to autofs_catatonic_mode()
as well, I'm still trying to grok if that change would cause side effects
for the change here but I think not.
Ian
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