From: Amit Shah <amit.shah@redhat.com>
To: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Cc: Anthony Liguori <aliguori@us.ibm.com>, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH] qed: fix use-after-free during l2 cache commit
Date: Fri, 30 Sep 2011 16:57:59 +0530 [thread overview]
Message-ID: <20110930112759.GI21901@amit-x200.redhat.com> (raw)
In-Reply-To: <1317379151-11557-1-git-send-email-stefanha@linux.vnet.ibm.com>
On (Fri) 30 Sep 2011 [11:39:11], Stefan Hajnoczi wrote:
> QED's metadata caching strategy allows two parallel requests to race for
> metadata lookup. The first one to complete will populate the metadata
> cache and the second one will drop the data it just read in favor of the
> cached data.
>
> There is a use-after-free in qed_read_l2_table_cb() and
> qed_commit_l2_update() where l2_table->offset was used after the
> l2_table may have been freed due to a metadata lookup race. Fix this by
> keeping the l2_offset in a local variable and not reaching into the
> possibly freed l2_table.
>
> Reported-by: Amit Shah <amit.shah@redhat.com>
> Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
> ---
> Hi Amit,
> Thanks for reporting the assertion failure you saw at http://fpaste.org/CDuv/.
> Does this patch fix the problem?
Yes, this fixes it.
Thanks,
Amit
next prev parent reply other threads:[~2011-09-30 11:29 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-30 10:39 [Qemu-devel] [PATCH] qed: fix use-after-free during l2 cache commit Stefan Hajnoczi
2011-09-30 11:27 ` Amit Shah [this message]
2011-09-30 15:23 ` Stefan Hajnoczi
2011-09-30 15:49 ` Amit Shah
2011-10-11 14:22 ` Kevin Wolf
2011-10-12 7:53 ` Stefan Hajnoczi
2011-09-30 15:26 ` Stefan Hajnoczi
2011-10-03 19:53 ` Anthony Liguori
2011-10-05 16:17 ` Anthony Liguori
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