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

------------------

From: NeilBrown <ne...@suse.de>

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 <s...@nowaker.net>
URL: https://bugzilla.kernel.org/show_bug.cgi?id=68181
Signed-off-by: NeilBrown <ne...@suse.de>
Signed-off-by: Kamal Mostafa <ka...@canonical.com>
---
 drivers/md/raid10.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 4b4e094..dfd6eba 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -3153,10 +3153,6 @@ static sector_t sync_request(struct mddev *mddev, 
sector_t sector_nr,
                        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)
@@ -3188,6 +3184,10 @@ static sector_t sync_request(struct mddev *mddev, 
sector_t sector_nr,
                                        mirror->recovery_disabled
                                                = mddev->recovery_disabled;
                                }
+                               put_buf(r10_bio);
+                               if (rb2)
+                                       atomic_dec(&rb2->remaining);
+                               r10_bio = rb2;
                                break;
                        }
                }
-- 
1.8.3.2

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