md: raid10: fix use-after-free of bio

In case of read errors raid10d tries to print a nice error message,
unfortunately using data from an already put bio.

Signed-off-by: Maik Hampel <m.hampel@gmx.de>
Acked-By: NeilBrown <neilb@suse.de>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index f730a144baf1..0c97bf4f686e 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -1557,7 +1557,6 @@ static void raid10d(mddev_t *mddev)
                         bio = r10_bio->devs[r10_bio->read_slot].bio;
                         r10_bio->devs[r10_bio->read_slot].bio =
                                 mddev->ro ? IO_BLOCKED : NULL;
-                        bio_put(bio);
                         mirror = read_balance(conf, r10_bio);
                         if (mirror == -1) {
                                 printk(KERN_ALERT "raid10: %s: unrecoverable I/O"
@@ -1565,8 +1564,10 @@ static void raid10d(mddev_t *mddev)
                                        bdevname(bio->bi_bdev,b),
                                        (unsigned long long)r10_bio->sector);
                                 raid_end_bio_io(r10_bio);
+                                bio_put(bio);
                         } else {
                                 const int do_sync = bio_sync(r10_bio->master_bio);
+                                bio_put(bio);
                                 rdev = conf->mirrors[mirror].rdev;
                                 if (printk_ratelimit())
                                         printk(KERN_ERR "raid10: %s: redirecting sector %llu to"