This is a note to let you know that I've just added the patch titled
md/raid10: remove use-after-free bug.
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
md-raid10-remove-use-after-free-bug.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 0eb25bb027a100f5a9df8991f2f628e7d851bc1e Mon Sep 17 00:00:00 2001
From: NeilBrown <neilb@xxxxxxx>
Date: Wed, 24 Jul 2013 15:37:42 +1000
Subject: md/raid10: remove use-after-free bug.
From: NeilBrown <neilb@xxxxxxx>
commit 0eb25bb027a100f5a9df8991f2f628e7d851bc1e upstream.
We always need to be careful when calling generic_make_request, as it
can start a chain of events which might free something that we are
using.
Here is one place I wasn't careful enough. If the wbio2 is not in
use, then it might get freed at the first generic_make_request call.
So perform all necessary tests first.
This bug was introduced in 3.3-rc3 (24afd80d99) and can cause an
oops, so fix is suitable for any -stable since then.
Signed-off-by: NeilBrown <neilb@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/md/raid10.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -2029,12 +2029,18 @@ static void recovery_request_write(struc
d = r10_bio->devs[1].devnum;
wbio = r10_bio->devs[1].bio;
wbio2 = r10_bio->devs[1].repl_bio;
+ /* Need to test wbio2->bi_end_io before we call
+ * generic_make_request as if the former is NULL,
+ * the latter is free to free wbio2.
+ */
+ if (wbio2 && !wbio2->bi_end_io)
+ wbio2 = NULL;
if (wbio->bi_end_io) {
atomic_inc(&conf->mirrors[d].rdev->nr_pending);
md_sync_acct(conf->mirrors[d].rdev->bdev, wbio->bi_size >> 9);
generic_make_request(wbio);
}
- if (wbio2 && wbio2->bi_end_io) {
+ if (wbio2) {
atomic_inc(&conf->mirrors[d].replacement->nr_pending);
md_sync_acct(conf->mirrors[d].replacement->bdev,
wbio2->bi_size >> 9);
Patches currently in stable-queue which might be from neilb@xxxxxxx are
queue-3.4/md-raid10-remove-use-after-free-bug.patch
queue-3.4/md-raid5-fix-interaction-of-replace-and-recovery.patch
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