From: Catalin Marinas <catalin.marinas@arm.com>
To: CAI Qian <caiqian@redhat.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Andy Lutomirski <luto@kernel.org>
Subject: Re: [PATCH] mm: kmemleak: Ensure that the task stack is not freed during scanning
Date: Wed, 12 Oct 2016 17:14:41 +0100 [thread overview]
Message-ID: <20161012161441.GC21592@e104818-lin.cambridge.arm.com> (raw)
In-Reply-To: <2086376822.528054.1476287657078.JavaMail.zimbra@redhat.com>
On Wed, Oct 12, 2016 at 11:54:17AM -0400, CAI Qian wrote:
> ----- Original Message -----
> > From: "Catalin Marinas" <catalin.marinas@arm.com>
> > To: linux-mm@kvack.org
> > Cc: linux-kernel@vger.kernel.org, "Andrew Morton" <akpm@linux-foundation.org>, "Andy Lutomirski" <luto@kernel.org>,
> > "CAI Qian" <caiqian@redhat.com>
> > Sent: Wednesday, October 12, 2016 5:57:03 AM
> > Subject: [PATCH] mm: kmemleak: Ensure that the task stack is not freed during scanning
> >
> > Commit 68f24b08ee89 ("sched/core: Free the stack early if
> > CONFIG_THREAD_INFO_IN_TASK") may cause the task->stack to be freed
> > during kmemleak_scan() execution, leading to either a NULL pointer
> > fault (if task->stack is NULL) or kmemleak accessing already freed
> > memory. This patch uses the new try_get_task_stack() API to ensure that
> > the task stack is not freed during kmemleak stack scanning.
> >
> > Fixes: 68f24b08ee89 ("sched/core: Free the stack early if
> > CONFIG_THREAD_INFO_IN_TASK")
> > Cc: Andrew Morton <akpm@linux-foundation.org>
> > Cc: Andy Lutomirski <luto@kernel.org>
> > Cc: CAI Qian <caiqian@redhat.com>
> > Reported-by: CAI Qian <caiqian@redhat.com>
> > Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
>
> Tested-by: CAI Qian <caiqian@redhat.com>
Thanks.
BTW, I noticed a few false positives reported by kmemleak with the
CONFIG_VMAP_STACK enabled caused by the fact that kmemleak requires two
references (instead of one) to a vmalloc'ed object because of the
vm_struct already containing the address. The cached_stack[] array only
stores the vm_struct rather than the stack address, hence the kmemleak
report. I'll work on a fix/annotation.
--
Catalin
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next prev parent reply other threads:[~2016-10-12 16:14 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-12 9:57 Catalin Marinas
2016-10-12 10:16 ` Hillf Danton
2016-10-12 10:47 ` Catalin Marinas
2016-10-12 10:41 ` Michal Hocko
2016-10-12 15:54 ` CAI Qian
2016-10-12 16:14 ` Catalin Marinas [this message]
2016-10-19 18:33 ` Andrew Morton
2016-10-20 10:02 ` Catalin Marinas
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