From: Colin Ian King <colin.king@xxxxxxxxxxxxx>
The bio pointer is being null checked hence it can be potentially null,
however earlier it is being derefefenced on the assignment of front_seg_size.
Avoid the dereference issue by only assigning front_seg_size after bios has
been null sanity checked.
Fixes: dcebd755926b ("block: use bio_for_each_bvec() to compute multi-page bvec count")
Signed-off-by: Colin Ian King <colin.king@xxxxxxxxxxxxx>
---
V2: remove front_seg_size assignment when it is declared
---
block/blk-merge.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/block/blk-merge.c b/block/blk-merge.c
index bed065904677..096947413ea9 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -363,7 +363,7 @@ static unsigned int __blk_recalc_rq_segments(struct request_queue *q,
struct bio_vec bv, bvprv = { NULL };
int prev = 0;
unsigned int seg_size, nr_phys_segs;
- unsigned front_seg_size = bio->bi_seg_front_size;
+ unsigned front_seg_size;
struct bio *fbio, *bbio;
struct bvec_iter iter;
@@ -379,6 +379,7 @@ static unsigned int __blk_recalc_rq_segments(struct request_queue *q,
return 1;
}
+ front_seg_size = bio->bi_seg_front_size;
fbio = bio;
seg_size = 0;
nr_phys_segs = 0;
--
2.20.1
