On Thu, Sep 21, 2023 at 11:20:12AM -0700, Saranya Muruganandam wrote: > From: Ming Lei <ming.lei@xxxxxxxxxx> > > commit d36a9ea5e7766961e753ee38d4c331bbe6ef659b upstream. > > For blk-mq, queue release handler is usually called after > blk_mq_freeze_queue_wait() returns. However, the > q_usage_counter->release() handler may not be run yet at that time, so > this can cause a use-after-free. > > Fix the issue by moving percpu_ref_exit() into blk_free_queue_rcu(). > Since ->release() is called with rcu read lock held, it is agreed that > the race should be covered in caller per discussion from the two links. > > Backport-notes: Not a clean cherry-pick since a lot has changed, > however essentially the same fix. > > Reported-by: Zhang Wensheng <zhangwensheng@xxxxxxxxxxxxxxx> > Reported-by: Zhong Jinghua <zhongjinghua@xxxxxxxxxx> > Link: https://lore.kernel.org/linux-block/Y5prfOjyyjQKUrtH@T590/T/#u > Link: https://lore.kernel.org/lkml/Y4%2FmzMd4evRg9yDi@fedora/ > Cc: Hillf Danton <hdanton@xxxxxxxx> > Cc: Yu Kuai <yukuai3@xxxxxxxxxx> > Cc: Dennis Zhou <dennis@xxxxxxxxxx> > Fixes: 2b0d3d3e4fcf ("percpu_ref: reduce memory footprint of percpu_ref in fast path") > Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx> > Link: https://lore.kernel.org/r/20221215021629.74870-1-ming.lei@xxxxxxxxxx > Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> > Signed-off-by: Saranya Muruganandam <saranyamohan@xxxxxxxxxx> > --- > block/blk-core.c | 2 -- > block/blk-sysfs.c | 2 ++ > 2 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/block/blk-core.c b/block/blk-core.c > index d0d0dd8151f7..e5eeec801f56 100644 > --- a/block/blk-core.c > +++ b/block/blk-core.c > @@ -414,8 +414,6 @@ void blk_cleanup_queue(struct request_queue *q) > blk_mq_sched_free_requests(q); > mutex_unlock(&q->sysfs_lock); > > - percpu_ref_exit(&q->q_usage_counter); > - > /* @q is and will stay empty, shutdown and put */ > blk_put_queue(q); > } > diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c > index 8c5816364dd1..9174137a913c 100644 > --- a/block/blk-sysfs.c > +++ b/block/blk-sysfs.c > @@ -726,6 +726,8 @@ static void blk_free_queue_rcu(struct rcu_head *rcu_head) > { > struct request_queue *q = container_of(rcu_head, struct request_queue, > rcu_head); > + > + percpu_ref_exit(&q->q_usage_counter); > kmem_cache_free(blk_requestq_cachep, q); > } Looks fine. BTW, you should have provided target stable tree release info, otherwise how you expect people to review? Thanks, Ming
