block: ensure to split after potentially bouncing a bio (Closes: #809082)

debian/changelog

@@ -2,6 +2,7 @@ linux (4.3.3-3) UNRELEASED; urgency=medium
 
   [ Ben Hutchings ]
   * [ppc64*] drm: Enable DRM_AST as module (Closes: #808338)
+  * block: ensure to split after potentially bouncing a bio (Closes: #809082)
 
   [ Salvatore Bonaccorso ]
   * ovl: fix permission checking for setattr (CVE-2015-8660)

debian/patches/bugfix/all/block-ensure-to-split-after-potentially-bouncing-a-b.patch

@@ -0,0 +1,39 @@
+From: Junichi Nomura <j-nomura@ce.jp.nec.com>
+Date: Tue, 22 Dec 2015 10:23:44 -0700
+Subject: block: ensure to split after potentially bouncing a bio
+Origin: https://git.kernel.org/linus/23688bf4f830a89866fd0ed3501e342a7360fe4f
+Bug-Debian: https://bugs.debian.org/809082
+
+blk_queue_bio() does split then bounce, which makes the segment
+counting based on pages before bouncing and could go wrong. Move
+the split to after bouncing, like we do for blk-mq, and the we
+fix the issue of having the bio count for segments be wrong.
+
+Fixes: 54efd50bfd87 ("block: make generic_make_request handle arbitrarily sized bios")
+Cc: stable@vger.kernel.org
+Tested-by: Artem S. Tashkinov <t.artem@lycos.com>
+Signed-off-by: Jens Axboe <axboe@fb.com>
+---
+ block/blk-core.c | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+--- a/block/blk-core.c
++++ b/block/blk-core.c
+@@ -1616,8 +1616,6 @@ static void blk_queue_bio(struct request
+ 	struct request *req;
+ 	unsigned int request_count = 0;
+ 
+-	blk_queue_split(q, &bio, q->bio_split);
+-
+ 	/*
+ 	 * low level driver can indicate that it wants pages above a
+ 	 * certain limit bounced to low memory (ie for highmem, or even
+@@ -1625,6 +1623,8 @@ static void blk_queue_bio(struct request
+ 	 */
+ 	blk_queue_bounce(q, &bio);
+ 
++	blk_queue_split(q, &bio, q->bio_split);
++
+ 	if (bio_integrity_enabled(bio) && bio_integrity_prep(bio)) {
+ 		bio->bi_error = -EIO;
+ 		bio_endio(bio);

debian/patches/series

@@ -106,3 +106,4 @@ bugfix/all/vrf-fix-double-free-and-memory-corruption-on-registe.patch
 bugfix/all/tipc-fix-kfree_skb-of-uninitialised-pointer.patch
 debian/armhf-sparc64-force-zone_dma-to-be-enabled.patch
 bugfix/all/ovl-fix-permission-checking-for-setattr.patch
+bugfix/all/block-ensure-to-split-after-potentially-bouncing-a-b.patch