From: Dmitry Vyukov <dvyukov@google.com>
To: Johannes Berg <johannes@sipsolutions.net>
Cc: David Gow <davidgow@google.com>,
Vincent Whitchurch <vincent.whitchurch@axis.com>,
Patricia Alfonso <trishalfonso@google.com>,
Jeff Dike <jdike@addtoit.com>,
Richard Weinberger <richard@nod.at>,
anton.ivanov@cambridgegreys.com,
Brendan Higgins <brendanhiggins@google.com>,
kasan-dev <kasan-dev@googlegroups.com>,
linux-um@lists.infradead.org, LKML <linux-kernel@vger.kernel.org>,
Daniel Latypov <dlatypov@google.com>
Subject: Re: [RFC PATCH v3] UML: add support for KASAN under x86_64
Date: Fri, 27 May 2022 15:52:12 +0200 [thread overview]
Message-ID: <CACT4Y+aH7LqDUqAyQ7+hkyeZTtkYnMHia73M7=EeAzMYzJ8pQg@mail.gmail.com> (raw)
In-Reply-To: <134957369d2e0abf51f03817f1e4de7cbf21f76e.camel@sipsolutions.net>
On Fri, 27 May 2022 at 15:27, Johannes Berg <johannes@sipsolutions.net> wrote:
>
> On Fri, 2022-05-27 at 15:18 +0200, Dmitry Vyukov wrote:
> > On Fri, 27 May 2022 at 15:15, Johannes Berg <johannes@sipsolutions.net> wrote:
> > >
> > > On Fri, 2022-05-27 at 15:09 +0200, Dmitry Vyukov wrote:
> > > > > I did note (this is more for kasan-dev@) that the "freed by" is fairly
> > > > > much useless when using kfree_rcu(), it might be worthwhile to annotate
> > > > > that somehow, so the stack trace is recorded by kfree_rcu() already,
> > > > > rather than just showing the RCU callback used for that.
> > > >
> > > > KASAN is doing it for several years now, see e.g.:
> > > > https://groups.google.com/g/syzkaller-bugs/c/eTW9zom4O2o/m/_v7cOo2RFwAJ
> > > >
> > >
> > > Hm. It didn't for me:
> >
> > Please post a full report with line numbers and kernel version.
>
> That was basically it, apart from a few lines snipped from the stack
> traces. Kernel version was admittedly a little older - 5.18.0-rc1 + a
> few UML fixes + this KASAN patch (+ the fixes I pointed out earlier)
>
> I guess it doesn't really matter that much, just had to dig a bit to
> understand why it was freed.
Humm... I don't have any explanation based only on this info.
Generally call_rcu stacks are memorized and I see the call is still there:
https://elixir.bootlin.com/linux/v5.18/source/kernel/rcu/tree.c#L3595
It may be caused by some narrow races, depleted reserve memory in
stackdepot, or race with quarantine eviction.
WARNING: multiple messages have this Message-ID (diff)
From: Dmitry Vyukov <dvyukov@google.com>
To: Johannes Berg <johannes@sipsolutions.net>
Cc: David Gow <davidgow@google.com>,
Vincent Whitchurch <vincent.whitchurch@axis.com>,
Patricia Alfonso <trishalfonso@google.com>,
Jeff Dike <jdike@addtoit.com>,
Richard Weinberger <richard@nod.at>,
anton.ivanov@cambridgegreys.com,
Brendan Higgins <brendanhiggins@google.com>,
kasan-dev <kasan-dev@googlegroups.com>,
linux-um@lists.infradead.org, LKML <linux-kernel@vger.kernel.org>,
Daniel Latypov <dlatypov@google.com>
Subject: Re: [RFC PATCH v3] UML: add support for KASAN under x86_64
Date: Fri, 27 May 2022 15:52:12 +0200 [thread overview]
Message-ID: <CACT4Y+aH7LqDUqAyQ7+hkyeZTtkYnMHia73M7=EeAzMYzJ8pQg@mail.gmail.com> (raw)
In-Reply-To: <134957369d2e0abf51f03817f1e4de7cbf21f76e.camel@sipsolutions.net>
On Fri, 27 May 2022 at 15:27, Johannes Berg <johannes@sipsolutions.net> wrote:
>
> On Fri, 2022-05-27 at 15:18 +0200, Dmitry Vyukov wrote:
> > On Fri, 27 May 2022 at 15:15, Johannes Berg <johannes@sipsolutions.net> wrote:
> > >
> > > On Fri, 2022-05-27 at 15:09 +0200, Dmitry Vyukov wrote:
> > > > > I did note (this is more for kasan-dev@) that the "freed by" is fairly
> > > > > much useless when using kfree_rcu(), it might be worthwhile to annotate
> > > > > that somehow, so the stack trace is recorded by kfree_rcu() already,
> > > > > rather than just showing the RCU callback used for that.
> > > >
> > > > KASAN is doing it for several years now, see e.g.:
> > > > https://groups.google.com/g/syzkaller-bugs/c/eTW9zom4O2o/m/_v7cOo2RFwAJ
> > > >
> > >
> > > Hm. It didn't for me:
> >
> > Please post a full report with line numbers and kernel version.
>
> That was basically it, apart from a few lines snipped from the stack
> traces. Kernel version was admittedly a little older - 5.18.0-rc1 + a
> few UML fixes + this KASAN patch (+ the fixes I pointed out earlier)
>
> I guess it doesn't really matter that much, just had to dig a bit to
> understand why it was freed.
Humm... I don't have any explanation based only on this info.
Generally call_rcu stacks are memorized and I see the call is still there:
https://elixir.bootlin.com/linux/v5.18/source/kernel/rcu/tree.c#L3595
It may be caused by some narrow races, depleted reserve memory in
stackdepot, or race with quarantine eviction.
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next prev parent reply other threads:[~2022-05-27 13:52 UTC|newest]
Thread overview: 75+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-26 0:46 [PATCH] UML: add support for KASAN under x86_64 Patricia Alfonso
2020-02-26 0:46 ` Patricia Alfonso
2020-02-26 1:19 ` Brendan Higgins
2020-02-26 1:19 ` Brendan Higgins
2020-02-26 15:24 ` Dmitry Vyukov
2020-02-26 15:24 ` Dmitry Vyukov
2020-03-06 0:03 ` Patricia Alfonso
2020-03-06 0:03 ` Patricia Alfonso
2020-03-11 10:32 ` Johannes Berg
2020-03-11 10:32 ` Johannes Berg
2020-03-11 10:46 ` Dmitry Vyukov
2020-03-11 10:46 ` Dmitry Vyukov
2020-03-11 11:18 ` Johannes Berg
2020-03-11 11:18 ` Johannes Berg
2020-03-11 11:40 ` Johannes Berg
2020-03-11 11:40 ` Johannes Berg
2020-03-11 17:34 ` Dmitry Vyukov
2020-03-11 17:34 ` Dmitry Vyukov
2020-03-20 13:39 ` Johannes Berg
2020-03-20 13:39 ` Johannes Berg
2020-03-20 15:18 ` Dmitry Vyukov
2020-03-20 15:18 ` Dmitry Vyukov
2020-03-30 7:43 ` Johannes Berg
2020-03-30 7:43 ` Johannes Berg
2020-03-30 8:38 ` Dmitry Vyukov
2020-03-30 8:38 ` Dmitry Vyukov
2020-03-30 8:41 ` Johannes Berg
2020-03-30 8:41 ` Johannes Berg
2020-03-31 6:14 ` David Gow
2020-03-31 6:14 ` David Gow
2020-03-31 7:43 ` Johannes Berg
2020-03-31 7:43 ` Johannes Berg
2020-03-31 16:39 ` Patricia Alfonso
2020-03-31 16:39 ` Patricia Alfonso
2020-03-31 16:54 ` Richard Weinberger
2020-03-11 22:32 ` Patricia Alfonso
2020-03-11 22:32 ` Patricia Alfonso
2020-03-11 22:44 ` Johannes Berg
2020-03-11 22:44 ` Johannes Berg
2022-05-24 10:34 ` Vincent Whitchurch
2022-05-24 10:34 ` Vincent Whitchurch
2022-05-24 10:45 ` Johannes Berg
2022-05-24 10:45 ` Johannes Berg
2022-05-24 19:35 ` David Gow
2022-05-24 19:35 ` David Gow
2022-05-25 11:17 ` Vincent Whitchurch
2022-05-25 11:17 ` Vincent Whitchurch
2022-05-26 1:01 ` [RFC PATCH v3] " David Gow
2022-05-26 1:01 ` David Gow
2022-05-26 9:29 ` Johannes Berg
2022-05-26 9:29 ` Johannes Berg
2022-05-27 5:31 ` Dmitry Vyukov
2022-05-27 5:31 ` Dmitry Vyukov
2022-05-27 7:32 ` Johannes Berg
2022-05-27 7:32 ` Johannes Berg
2022-05-27 10:36 ` Johannes Berg
2022-05-27 10:36 ` Johannes Berg
2022-05-27 13:05 ` Johannes Berg
2022-05-27 13:05 ` Johannes Berg
2022-05-27 13:09 ` Dmitry Vyukov
2022-05-27 13:09 ` Dmitry Vyukov
2022-05-27 13:15 ` Johannes Berg
2022-05-27 13:15 ` Johannes Berg
2022-05-27 13:18 ` Dmitry Vyukov
2022-05-27 13:18 ` Dmitry Vyukov
2022-05-27 13:27 ` Johannes Berg
2022-05-27 13:27 ` Johannes Berg
2022-05-27 13:52 ` Dmitry Vyukov [this message]
2022-05-27 13:52 ` Dmitry Vyukov
2022-05-27 14:27 ` Johannes Berg
2022-05-27 14:27 ` Johannes Berg
2022-05-27 15:46 ` Dmitry Vyukov
2022-05-27 15:46 ` Dmitry Vyukov
2020-03-29 19:06 ` [PATCH] " Richard Weinberger
2020-03-29 19:06 ` Richard Weinberger
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