Re: page fault in pfioctl

From: Kristof Provost <kp_at_FreeBSD.org>
Date: Sat, 25 Sep 2021 18:34:42 +0200
On 25 Sep 2021, at 18:25, Andriy Gapon wrote:
> On 13/06/2021 11:19, Kristof Provost wrote:
>> On 13 Jun 2021, at 09:41, Andriy Gapon <avg_at_freebsd.org> wrote:
>>> Based on
>>> the panic message (page fault with non-sleepable locks held), it seems that
>>> the problem is with holding the lock across the copyout.  Usually that
>>> won't panic, but if the destination happens to be paged out... And only
>>> with INVARIANTS, I guess...
>>
>> Oh right. Thanks. I’ve gotten bitten by that one before, but had clearly
>> garbage collected the memory.
>>
>> I’ll fix this one and check for others on Monday.
>>
>> I’ll also see of we can persuade copyout to always panic on this bug, not
>> just when the destination memory is actually paged out. That way we’ll catch
>> this in the regression tests in the future.
>
> I upgraded to the latest stable/13 and hit a fresh panic of the same type.
> This time it's in pf_getstatus() and it's a copyout while 'pf rulesets' lock is held.
>
I believe that’s fixed by https://cgit.freebsd.org/src/commit/sys/netpfil/pf/pf_ioctl.c?id=cb13059663e455b3fc69c293dadec53c164490dc

Best regards,
Kristof
Received on Sat Sep 25 2021 - 16:34:42 UTC

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