From: Martin K. Petersen <martin.petersen@oracle.com>
Date: Wed, 9 Apr 2014 02:43:43 +0000 (-0400)
Subject: block: Fix for_each_bvec()
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=b7aa84d9cb9f26da1a9312c3e39dbd1a3c25a426;p=linux-beck.git

block: Fix for_each_bvec()

Commit 4550dd6c6b062 introduced for_each_bvec() which iterates over each
bvec attached to a bio or bip. However, the macro fails to check bi_size
before dereferencing which can lead to crashes while counting/mapping
integrity scatterlist segments.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Kent Overstreet <kmo@daterainc.com>
Cc: Nicholas Bellinger <nab@linux-iscsi.org>
Cc: <stable@vger.kernel.org> # v3.14+
Signed-off-by: Jens Axboe <axboe@fb.com>
---

diff --git a/include/linux/bio.h b/include/linux/bio.h
index 5a4d39b4686b..5aa372a7380c 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -216,9 +216,9 @@ static inline void bvec_iter_advance(struct bio_vec *bv, struct bvec_iter *iter,
 }
 
 #define for_each_bvec(bvl, bio_vec, iter, start)			\
-	for ((iter) = start;						\
-	     (bvl) = bvec_iter_bvec((bio_vec), (iter)),			\
-		(iter).bi_size;						\
+	for (iter = (start);						\
+	     (iter).bi_size &&						\
+		((bvl = bvec_iter_bvec((bio_vec), (iter))), 1);	\
 	     bvec_iter_advance((bio_vec), &(iter), (bvl).bv_len))