6.12-stable review patch. If anyone has any objections, please let me know.
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From: Ming Lei ming.lei@redhat.com
[ Upstream commit 85672ca9ceeaa1dcf2777a7048af5f4aee3fd02b ]
If the 'hctx' isn't removed from cpuhp callback list, we can't reuse it, otherwise use-after-free may be triggered.
Reported-by: kernel test robot oliver.sang@intel.com Closes: https://lore.kernel.org/oe-lkp/202412172217.b906db7c-lkp@intel.com Tested-by: kernel test robot oliver.sang@intel.com Fixes: 22465bbac53c ("blk-mq: move cpuhp callback registering out of q->sysfs_lock") Signed-off-by: Ming Lei ming.lei@redhat.com Link: https://lore.kernel.org/r/20241218101617.3275704-3-ming.lei@redhat.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org --- block/blk-mq.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/block/blk-mq.c b/block/blk-mq.c index 1030875a3e95..d5995021815d 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -4421,6 +4421,15 @@ struct gendisk *blk_mq_alloc_disk_for_queue(struct request_queue *q, } EXPORT_SYMBOL(blk_mq_alloc_disk_for_queue);
+/* + * Only hctx removed from cpuhp list can be reused + */ +static bool blk_mq_hctx_is_reusable(struct blk_mq_hw_ctx *hctx) +{ + return hlist_unhashed(&hctx->cpuhp_online) && + hlist_unhashed(&hctx->cpuhp_dead); +} + static struct blk_mq_hw_ctx *blk_mq_alloc_and_init_hctx( struct blk_mq_tag_set *set, struct request_queue *q, int hctx_idx, int node) @@ -4430,7 +4439,7 @@ static struct blk_mq_hw_ctx *blk_mq_alloc_and_init_hctx( /* reuse dead hctx first */ spin_lock(&q->unused_hctx_lock); list_for_each_entry(tmp, &q->unused_hctx_list, hctx_list) { - if (tmp->numa_node == node) { + if (tmp->numa_node == node && blk_mq_hctx_is_reusable(tmp)) { hctx = tmp; break; }