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 5a4d39b..5aa372a 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -216,9 +216,9 @@
}
#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))