From: Badari Pulavarty <pbadari@us.ibm.com>

Need to initialize map_bh.b_state to zero.  Otherwise, in case of a faulty
user-buffer its possible to go into dio_zero_block() and submit a page by
mistake - since it checks for buffer_new().

http://marc.info/?l=linux-kernel&m=118551339032528&w=2

Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com>
Cc: Joe Jin <joe.jin@oracle.com>
Cc: Zach Brown <zach.brown@oracle.com>
Cc: gurudas pai <gurudas.pai@oracle.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 fs/direct-io.c |    1 +
 1 files changed, 1 insertion(+)

diff -puN fs/direct-io.c~direct-io-fix-error-path-crashes fs/direct-io.c
--- a/fs/direct-io.c~direct-io-fix-error-path-crashes
+++ a/fs/direct-io.c
@@ -974,6 +974,7 @@ direct_io_worker(int rw, struct kiocb *i
 	dio->get_block = get_block;
 	dio->end_io = end_io;
 	dio->map_bh.b_private = NULL;
+	dio->map_bh.b_state = 0;
 	dio->final_block_in_bio = -1;
 	dio->next_block_for_io = -1;
 
_