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block: avoid to READ fields of null bio 

rq->bio can be NULL sometimes, such as flush request, so don't
read bio->bi_seg_front_size until this 'bio' is checked as valid.

Cc: Bart Van Assche <bvanassche@acm.org>
Reported-by: Bart Van Assche <bvanassche@acm.org>
Fixes: dcebd75592 ("block: use bio_for_each_bvec() to compute multi-page bvec count")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
hifive-unleashed-5.1
Ming Lei 2019-02-19 11:08:19 +08:00 committed by Jens Axboe
parent 6fb845f0e7
commit 49b1f22b56
1 changed files with 3 additions and 1 deletions
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4
block/blk-merge.c
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@ -363,13 +363,15 @@ 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;
if (!bio)
return 0;
front_seg_size = bio->bi_seg_front_size;
switch (bio_op(bio)) {
case REQ_OP_DISCARD:
case REQ_OP_SECURE_ERASE: