| Message ID | 20190219143702.11926-1-colin.king@canonical.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [next,V2] block: don't dereference a potential null bio pointer until is has been null checked | expand |
On Tue, Feb 19, 2019 at 02:37:02PM +0000, Colin King wrote: > From: Colin Ian King <colin.king@canonical.com> > > 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@canonical.com> > --- > > 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; Smatch says bio is non-NULL but I didn't verify by hand. regards, dan carpenter
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;