3.16-stable review patch. If anyone has any objections, please let me know. ------------------ From: David Hildenbrand <dahi@xxxxxxxxxxxxxxxxxx> commit 683d0e126232d898a481daa3a4ca032c2b1a9660 upstream. This patch should fix the bug reported in https://lkml.org/lkml/2014/9/11/249. We have to initialize at least the atomic_flags and the cmd_flags when allocating storage for the requests. Otherwise blk_mq_timeout_check() might dereference uninitialized pointers when racing with the creation of a request. Also move the reset of cmd_flags for the initializing code to the point where a request is freed. So we will never end up with pending flush request indicators that might trigger dereferences of invalid pointers in blk_mq_timeout_check(). Signed-off-by: David Hildenbrand <dahi@xxxxxxxxxxxxxxxxxx> Reported-by: Paulo De Rezende Pinatti <ppinatti@xxxxxxxxxxxxxxxxxx> Tested-by: Paulo De Rezende Pinatti <ppinatti@xxxxxxxxxxxxxxxxxx> Acked-by: Christian Borntraeger <borntraeger@xxxxxxxxxx> Signed-off-by: Jens Axboe <axboe@xxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- block/blk-mq.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -219,7 +219,6 @@ __blk_mq_alloc_request(struct blk_mq_all if (tag != BLK_MQ_TAG_FAIL) { rq = data->hctx->tags->rqs[tag]; - rq->cmd_flags = 0; if (blk_mq_tag_busy(data->hctx)) { rq->cmd_flags = REQ_MQ_INFLIGHT; atomic_inc(&data->hctx->nr_active); @@ -274,6 +273,7 @@ static void __blk_mq_free_request(struct if (rq->cmd_flags & REQ_MQ_INFLIGHT) atomic_dec(&hctx->nr_active); + rq->cmd_flags = 0; clear_bit(REQ_ATOM_STARTED, &rq->atomic_flags); blk_mq_put_tag(hctx, tag, &ctx->last_tag); @@ -1411,6 +1411,8 @@ static struct blk_mq_tags *blk_mq_init_r left -= to_do * rq_size; for (j = 0; j < to_do; j++) { tags->rqs[i] = p; + tags->rqs[i]->atomic_flags = 0; + tags->rqs[i]->cmd_flags = 0; if (set->ops->init_request) { if (set->ops->init_request(set->driver_data, tags->rqs[i], hctx_idx, i, -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html