From 1951180946b75f46ea24cb410d1b3f0362920afe Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Thu, 9 Sep 2021 12:07:31 +0200 Subject: [PATCH] 5.13-stable patches added patches: blk-mq-fix-is_flush_rq.patch blk-mq-fix-kernel-panic-during-iterating-over-flush-request.patch --- queue-5.13/blk-mq-fix-is_flush_rq.patch | 87 +++++++++++++++++++ ...-during-iterating-over-flush-request.patch | 73 ++++++++++++++++ queue-5.13/series | 2 + 3 files changed, 162 insertions(+) create mode 100644 queue-5.13/blk-mq-fix-is_flush_rq.patch create mode 100644 queue-5.13/blk-mq-fix-kernel-panic-during-iterating-over-flush-request.patch diff --git a/queue-5.13/blk-mq-fix-is_flush_rq.patch b/queue-5.13/blk-mq-fix-is_flush_rq.patch new file mode 100644 index 00000000000..84e3753d6f4 --- /dev/null +++ b/queue-5.13/blk-mq-fix-is_flush_rq.patch @@ -0,0 +1,87 @@ +From a9ed27a764156929efe714033edb3e9023c5f321 Mon Sep 17 00:00:00 2001 +From: Ming Lei +Date: Wed, 18 Aug 2021 09:09:25 +0800 +Subject: blk-mq: fix is_flush_rq + +From: Ming Lei + +commit a9ed27a764156929efe714033edb3e9023c5f321 upstream. + +is_flush_rq() is called from bt_iter()/bt_tags_iter(), and runs the +following check: + + hctx->fq->flush_rq == req + +but the passed hctx from bt_iter()/bt_tags_iter() may be NULL because: + +1) memory re-order in blk_mq_rq_ctx_init(): + + rq->mq_hctx = data->hctx; + ... + refcount_set(&rq->ref, 1); + +OR + +2) tag re-use and ->rqs[] isn't updated with new request. + +Fix the issue by re-writing is_flush_rq() as: + + return rq->end_io == flush_end_io; + +which turns out simpler to follow and immune to data race since we have +ordered WRITE rq->end_io and refcount_set(&rq->ref, 1). + +Fixes: 2e315dc07df0 ("blk-mq: grab rq->refcount before calling ->fn in blk_mq_tagset_busy_iter") +Cc: "Blank-Burian, Markus, Dr." +Cc: Yufen Yu +Signed-off-by: Ming Lei +Link: https://lore.kernel.org/r/20210818010925.607383-1-ming.lei@redhat.com +Signed-off-by: Jens Axboe +Cc: Yi Zhang +Signed-off-by: Greg Kroah-Hartman +--- + block/blk-flush.c | 5 +++++ + block/blk-mq.c | 2 +- + block/blk.h | 6 +----- + 3 files changed, 7 insertions(+), 6 deletions(-) + +--- a/block/blk-flush.c ++++ b/block/blk-flush.c +@@ -262,6 +262,11 @@ static void flush_end_io(struct request + spin_unlock_irqrestore(&fq->mq_flush_lock, flags); + } + ++bool is_flush_rq(struct request *rq) ++{ ++ return rq->end_io == flush_end_io; ++} ++ + /** + * blk_kick_flush - consider issuing flush request + * @q: request_queue being kicked +--- a/block/blk-mq.c ++++ b/block/blk-mq.c +@@ -911,7 +911,7 @@ static bool blk_mq_req_expired(struct re + + void blk_mq_put_rq_ref(struct request *rq) + { +- if (is_flush_rq(rq, rq->mq_hctx)) ++ if (is_flush_rq(rq)) + rq->end_io(rq, 0); + else if (refcount_dec_and_test(&rq->ref)) + __blk_mq_free_request(rq); +--- a/block/blk.h ++++ b/block/blk.h +@@ -44,11 +44,7 @@ static inline void __blk_get_queue(struc + kobject_get(&q->kobj); + } + +-static inline bool +-is_flush_rq(struct request *req, struct blk_mq_hw_ctx *hctx) +-{ +- return hctx->fq->flush_rq == req; +-} ++bool is_flush_rq(struct request *req); + + struct blk_flush_queue *blk_alloc_flush_queue(int node, int cmd_size, + gfp_t flags); diff --git a/queue-5.13/blk-mq-fix-kernel-panic-during-iterating-over-flush-request.patch b/queue-5.13/blk-mq-fix-kernel-panic-during-iterating-over-flush-request.patch new file mode 100644 index 00000000000..7abfa4465f3 --- /dev/null +++ b/queue-5.13/blk-mq-fix-kernel-panic-during-iterating-over-flush-request.patch @@ -0,0 +1,73 @@ +From c2da19ed50554ce52ecbad3655c98371fe58599f Mon Sep 17 00:00:00 2001 +From: Ming Lei +Date: Wed, 11 Aug 2021 22:26:24 +0800 +Subject: blk-mq: fix kernel panic during iterating over flush request + +From: Ming Lei + +commit c2da19ed50554ce52ecbad3655c98371fe58599f upstream. + +For fixing use-after-free during iterating over requests, we grabbed +request's refcount before calling ->fn in commit 2e315dc07df0 ("blk-mq: +grab rq->refcount before calling ->fn in blk_mq_tagset_busy_iter"). +Turns out this way may cause kernel panic when iterating over one flush +request: + +1) old flush request's tag is just released, and this tag is reused by +one new request, but ->rqs[] isn't updated yet + +2) the flush request can be re-used for submitting one new flush command, +so blk_rq_init() is called at the same time + +3) meantime blk_mq_queue_tag_busy_iter() is called, and old flush request +is retrieved from ->rqs[tag]; when blk_mq_put_rq_ref() is called, +flush_rq->end_io may not be updated yet, so NULL pointer dereference +is triggered in blk_mq_put_rq_ref(). + +Fix the issue by calling refcount_set(&flush_rq->ref, 1) after +flush_rq->end_io is set. So far the only other caller of blk_rq_init() is +scsi_ioctl_reset() in which the request doesn't enter block IO stack and +the request reference count isn't used, so the change is safe. + +Fixes: 2e315dc07df0 ("blk-mq: grab rq->refcount before calling ->fn in blk_mq_tagset_busy_iter") +Reported-by: "Blank-Burian, Markus, Dr." +Tested-by: "Blank-Burian, Markus, Dr." +Signed-off-by: Ming Lei +Reviewed-by: Christoph Hellwig +Reviewed-by: John Garry +Link: https://lore.kernel.org/r/20210811142624.618598-1-ming.lei@redhat.com +Signed-off-by: Jens Axboe +Cc: Yi Zhang +Signed-off-by: Greg Kroah-Hartman +--- + block/blk-core.c | 1 - + block/blk-flush.c | 8 ++++++++ + 2 files changed, 8 insertions(+), 1 deletion(-) + +--- a/block/blk-core.c ++++ b/block/blk-core.c +@@ -122,7 +122,6 @@ void blk_rq_init(struct request_queue *q + rq->internal_tag = BLK_MQ_NO_TAG; + rq->start_time_ns = ktime_get_ns(); + rq->part = NULL; +- refcount_set(&rq->ref, 1); + blk_crypto_rq_set_defaults(rq); + } + EXPORT_SYMBOL(blk_rq_init); +--- a/block/blk-flush.c ++++ b/block/blk-flush.c +@@ -329,6 +329,14 @@ static void blk_kick_flush(struct reques + flush_rq->rq_flags |= RQF_FLUSH_SEQ; + flush_rq->rq_disk = first_rq->rq_disk; + flush_rq->end_io = flush_end_io; ++ /* ++ * Order WRITE ->end_io and WRITE rq->ref, and its pair is the one ++ * implied in refcount_inc_not_zero() called from ++ * blk_mq_find_and_get_req(), which orders WRITE/READ flush_rq->ref ++ * and READ flush_rq->end_io ++ */ ++ smp_wmb(); ++ refcount_set(&flush_rq->ref, 1); + + blk_flush_queue_rq(flush_rq, false); + } diff --git a/queue-5.13/series b/queue-5.13/series index 066342391c2..8d7aaf9e7af 100644 --- a/queue-5.13/series +++ b/queue-5.13/series @@ -2,3 +2,5 @@ firmware-dmi-move-product_sku-info-to-the-end-of-the-modalias.patch igmp-add-ip_mc_list-lock-in-ip_check_mc_rcu.patch net-ll_temac-remove-left-over-debug-message.patch revert-r8169-avoid-link-up-interrupt-issue-on-rtl8106e-if-user-enables-aspm.patch +blk-mq-fix-kernel-panic-during-iterating-over-flush-request.patch +blk-mq-fix-is_flush_rq.patch -- 2.47.3