direct-io: fix error-path crashes

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

akpm: Linus had a (better) patch to just do a kzalloc() in there, but it got
lost.  Probably this version is better for -stable anwyay.

Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com>
Acked-by: Joe Jin <joe.jin@oracle.com>
Acked-by: 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>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/fs/direct-io.c b/fs/direct-io.c
index 52bb2638f7ab..6874785bb65a 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -974,6 +974,7 @@ direct_io_worker(int rw, struct kiocb *iocb, struct inode *inode,
         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;