* [PATCH] blk-mq: Avoid race condition with uninitialized requests @ 2014-09-18 9:04 David Hildenbrand 2014-09-18 9:04 ` David Hildenbrand 0 siblings, 1 reply; 5+ messages in thread From: David Hildenbrand @ 2014-09-18 9:04 UTC (permalink / raw) To: tom.leiming, axboe Cc: kvm, stable, borntraeger, rusty, virtualization, mst, dahi, linux-kernel This patch should fix the bug reported in https://lkml.org/lkml/2014/9/11/249. Test is still pending. David Hildenbrand (1): blk-mq: Avoid race condition with uninitialized requests block/blk-mq.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) -- 1.8.5.5 ^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH] blk-mq: Avoid race condition with uninitialized requests 2014-09-18 9:04 [PATCH] blk-mq: Avoid race condition with uninitialized requests David Hildenbrand @ 2014-09-18 9:04 ` David Hildenbrand 2014-09-19 12:41 ` Christian Borntraeger 2014-09-22 14:15 ` Christian Borntraeger 0 siblings, 2 replies; 5+ messages in thread From: David Hildenbrand @ 2014-09-18 9:04 UTC (permalink / raw) To: tom.leiming, axboe Cc: kvm, stable, borntraeger, rusty, virtualization, mst, dahi, linux-kernel 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@vger.kernel.org Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com> --- 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, -- 1.8.5.5 ^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] blk-mq: Avoid race condition with uninitialized requests 2014-09-18 9:04 ` David Hildenbrand @ 2014-09-19 12:41 ` Christian Borntraeger 2014-09-22 14:15 ` Christian Borntraeger 1 sibling, 0 replies; 5+ messages in thread From: Christian Borntraeger @ 2014-09-19 12:41 UTC (permalink / raw) To: David Hildenbrand, tom.leiming, axboe Cc: kvm, stable, rusty, virtualization, mst, linux-kernel 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@vger.kernel.org > Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com> So far our testers were not able to reproduce the problem with this patch applied, we will continue testing over weekend. I will give an ACK/NACK on monday then. Thanks > --- > 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, > ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] blk-mq: Avoid race condition with uninitialized requests 2014-09-18 9:04 ` David Hildenbrand 2014-09-19 12:41 ` Christian Borntraeger @ 2014-09-22 14:15 ` Christian Borntraeger 2014-09-22 14:17 ` Jens Axboe 1 sibling, 1 reply; 5+ messages in thread From: Christian Borntraeger @ 2014-09-22 14:15 UTC (permalink / raw) To: tom.leiming, axboe Cc: David Hildenbrand, kvm, stable, rusty, virtualization, mst, linux-kernel, ppinatti 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@vger.kernel.org > Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com> Acked-by: Christian Borntraeger <borntraeger@de.ibm.com> Can you please add Reported-by: Paulo De Rezende Pinatti <ppinatti@linux.vnet.ibm.com> Tested-by: Paulo De Rezende Pinatti <ppinatti@linux.vnet.ibm.com> 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, > ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] blk-mq: Avoid race condition with uninitialized requests 2014-09-22 14:15 ` Christian Borntraeger @ 2014-09-22 14:17 ` Jens Axboe 0 siblings, 0 replies; 5+ messages in thread From: Jens Axboe @ 2014-09-22 14:17 UTC (permalink / raw) To: Christian Borntraeger, tom.leiming Cc: David Hildenbrand, kvm, stable, rusty, virtualization, mst, linux-kernel, ppinatti On 2014-09-22 08:15, Christian Borntraeger wrote: > 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@vger.kernel.org >> Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com> > > Acked-by: Christian Borntraeger <borntraeger@de.ibm.com> > > Can you please add > Reported-by: Paulo De Rezende Pinatti <ppinatti@linux.vnet.ibm.com> > Tested-by: Paulo De Rezende Pinatti <ppinatti@linux.vnet.ibm.com> > > as Paulo did the testing work? > > We thing this patch is fine and should go upstream. I might have to pick'n rebase the series, in which case I'll add it. But I already queued it up last week, so if I don't, then I can't easily add it. I wish the git notes wasn't such a horrible and unusable hack, so we had a chance to annotate commits without having to rewrite history... -- Jens Axboe ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2014-09-22 14:17 UTC | newest] Thread overview: 5+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2014-09-18 9:04 [PATCH] blk-mq: Avoid race condition with uninitialized requests David Hildenbrand 2014-09-18 9:04 ` David Hildenbrand 2014-09-19 12:41 ` Christian Borntraeger 2014-09-22 14:15 ` Christian Borntraeger 2014-09-22 14:17 ` Jens Axboe
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