6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ming Lei <ming.lei@xxxxxxxxxx> commit 85672ca9ceeaa1dcf2777a7048af5f4aee3fd02b upstream. 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@xxxxxxxxx> Closes: https://lore.kernel.org/oe-lkp/202412172217.b906db7c-lkp@xxxxxxxxx Tested-by: kernel test robot <oliver.sang@xxxxxxxxx> Fixes: 22465bbac53c ("blk-mq: move cpuhp callback registering out of q->sysfs_lock") Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx> Link: https://lore.kernel.org/r/20241218101617.3275704-3-ming.lei@xxxxxxxxxx Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- block/blk-mq.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -4278,6 +4278,15 @@ struct gendisk *blk_mq_alloc_disk_for_qu } 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) @@ -4287,7 +4296,7 @@ static struct blk_mq_hw_ctx *blk_mq_allo /* 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; }
