From: "Martin K. Petersen" <[email protected]>

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 <[email protected]>
Cc: Kent Overstreet <[email protected]>
Cc: Nicholas Bellinger <[email protected]>
Cc: <[email protected]> # v3.14+
---
 include/linux/bio.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

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))
 
 
-- 
1.8.3.1

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