[patch 08/12] direct-io: fix error-path crashes

[Greg KH <gregkh@suse.de>]

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

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

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

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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

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

--- a/fs/direct-io.c
+++ b/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;
 

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