dm crypt: fix avoid cloned bio ref after free

Do not access the bio after generic_make_request

We should never access a bio after generic_make_request - there's no guarantee
it still exists.

Signed-off-by: Olaf Kirch <olaf.kirch@oracle.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 1 deletions

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index db439363f97d..1dc2c62200ee 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -655,9 +655,12 @@ static void process_write(struct crypt_io *io)
 
                 generic_make_request(clone);
 
+                /* Do not reference clone after this - it
+                 * may be gone already. */
+
                 /* out of memory -> run queues */
                 if (remaining)
-                        congestion_wait(bio_data_dir(clone), HZ/100);
+                        congestion_wait(WRITE, HZ/100);
         }
 }