[PATCH 3.12 20/27] md/raid10: fix bug when raid10 recovery fails to recover a block.

From: Greg Kroah-Hartman
Date: Thu Jan 23 2014 - 14:16:52 EST

3.12-stable review patch. If anyone has any objections, please let me know.


From: NeilBrown <neilb@xxxxxxx>

commit e8b849158508565e0cd6bc80061124afc5879160 upstream.

commit e875ecea266a543e643b19e44cf472f1412708f9
md/raid10 record bad blocks as needed during recovery.

added code to the "cannot recover this block" path to record a bad
block rather than fail the whole recovery.
Unfortunately this new case was placed *after* r10bio was freed rather
than *before*, yet it still uses r10bio.
This is will crash with a null dereference.

So move the freeing of r10bio down where it is safe.

Fixes: e875ecea266a543e643b19e44cf472f1412708f9
Reported-by: Damian Nowak <spam@xxxxxxxxxxx>
URL: https://bugzilla.kernel.org/show_bug.cgi?id=68181
Signed-off-by: NeilBrown <neilb@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

drivers/md/raid10.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -3220,10 +3220,6 @@ static sector_t sync_request(struct mdde
if (j == conf->copies) {
/* Cannot recover, so abort the recovery or
* record a bad block */
- put_buf(r10_bio);
- if (rb2)
- atomic_dec(&rb2->remaining);
- r10_bio = rb2;
if (any_working) {
/* problem is that there are bad blocks
* on other device(s)
@@ -3255,6 +3251,10 @@ static sector_t sync_request(struct mdde
= mddev->recovery_disabled;
+ put_buf(r10_bio);
+ if (rb2)
+ atomic_dec(&rb2->remaining);
+ r10_bio = rb2;

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