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
