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Commit 49b1f22b authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe
Browse files

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: default avatarBart Van Assche <bvanassche@acm.org>
Fixes: dcebd755 ("block: use bio_for_each_bvec() to compute multi-page bvec count")
Signed-off-by: default avatarMing Lei <ming.lei@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 6fb845f0

block/blk-merge.c

+3 −1
Original line number Diff line number Diff line
@@ -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: