diff options
| author | David Hildenbrand <dahi@linux.vnet.ibm.com> | 2014-09-18 11:04:31 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-10-05 13:41:09 -0700 |
| commit | 526d1f369185226566cdc5718650006e8e6fff73 (patch) | |
| tree | df7fb32fd72282a111b42cccb574a25e3dfececf | |
| parent | c1672332cb58921703d910b647bf9114a410fad7 (diff) | |
blk-mq: Avoid race condition with uninitialized requests
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@linux.vnet.ibm.com>
Reported-by: Paulo De Rezende Pinatti <ppinatti@linux.vnet.ibm.com>
Tested-by: Paulo De Rezende Pinatti <ppinatti@linux.vnet.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | block/blk-mq.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/block/blk-mq.c b/block/blk-mq.c index ad69ef657e85..06ac59f5bb5a 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -219,7 +219,6 @@ __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); @@ -274,6 +273,7 @@ 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); @@ -1411,6 +1411,8 @@ 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, |