On 09/18/2014 11:04 AM, David Hildenbrand wrote: > 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(). > > Cc: stable@xxxxxxxxxxxxxxx > Signed-off-by: David Hildenbrand <dahi@xxxxxxxxxxxxxxxxxx> Acked-by: Christian Borntraeger <borntraeger@xxxxxxxxxx> Can you please add Reported-by: Paulo De Rezende Pinatti <ppinatti@xxxxxxxxxxxxxxxxxx> Tested-by: Paulo De Rezende Pinatti <ppinatti@xxxxxxxxxxxxxxxxxx> as Paulo did the testing work? We thing this patch is fine and should go upstream. Christian > --- > block/blk-mq.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/block/blk-mq.c b/block/blk-mq.c > index 383ea0c..eed6340 100644 > --- a/block/blk-mq.c > +++ b/block/blk-mq.c > @@ -203,7 +203,6 @@ __blk_mq_alloc_request(struct blk_mq_alloc_data *data, int rw) > 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); > @@ -258,6 +257,7 @@ static void __blk_mq_free_request(struct blk_mq_hw_ctx *hctx, > > 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); > @@ -1404,6 +1404,8 @@ static struct blk_mq_tags *blk_mq_init_rq_map(struct blk_mq_tag_set *set, > 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 kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
