| Message ID | 20230908005702.2183908-1-chengming.zhou@linux.dev (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | blk-mq: fix tags UAF when shrink nr_hw_queues | expand |
On 9/8/23 02:57, chengming.zhou@linux.dev wrote: > From: Chengming Zhou <zhouchengming@bytedance.com> > > When nr_hw_queues shrink, we free the excess tags before realloc > hw_ctxs for each queue, during that we may need to access those > tags, like blk_mq_tag_idle(hctx) will access queue shared tags. > > So slab-use-after-free caused and reported by KASAN. Fix it by > moving the releasing of excess tags to the end. > > Fixes: e1dd7bc93029 ("blk-mq: fix tags leak when shrink nr_hw_queues") > Reported-by: Yi Zhang <yi.zhang@redhat.com> > Closes: https://lore.kernel.org/all/CAHj4cs_CK63uoDpGBGZ6DN4OCTpzkR3UaVgK=LX8Owr8ej2ieQ@mail.gmail.com/ > Cc: Ming Lei <ming.lei@redhat.com> > Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com> > --- > block/blk-mq.c | 13 +++++++------ > 1 file changed, 7 insertions(+), 6 deletions(-) > Reviewed-by: Hannes Reinecke <hare@suse.de> Cheers, Hannes
On Fri, 08 Sep 2023 08:57:02 +0800, chengming.zhou@linux.dev wrote: > When nr_hw_queues shrink, we free the excess tags before realloc > hw_ctxs for each queue, during that we may need to access those > tags, like blk_mq_tag_idle(hctx) will access queue shared tags. > > So slab-use-after-free caused and reported by KASAN. Fix it by > moving the releasing of excess tags to the end. > > [...] Applied, thanks! [1/1] blk-mq: fix tags UAF when shrink nr_hw_queues (no commit info) Best regards,
diff --git a/block/blk-mq.c b/block/blk-mq.c index ec922c6bccbe..1fafd54dce3c 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -4405,11 +4405,8 @@ static int blk_mq_realloc_tag_set_tags(struct blk_mq_tag_set *set, struct blk_mq_tags **new_tags; int i; - if (set->nr_hw_queues >= new_nr_hw_queues) { - for (i = new_nr_hw_queues; i < set->nr_hw_queues; i++) - __blk_mq_free_map_and_rqs(set, i); + if (set->nr_hw_queues >= new_nr_hw_queues) goto done; - } new_tags = kcalloc_node(new_nr_hw_queues, sizeof(struct blk_mq_tags *), GFP_KERNEL, set->numa_node); @@ -4719,7 +4716,8 @@ static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, { struct request_queue *q; LIST_HEAD(head); - int prev_nr_hw_queues; + int prev_nr_hw_queues = set->nr_hw_queues; + int i; lockdep_assert_held(&set->tag_list_lock); @@ -4746,7 +4744,6 @@ static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, blk_mq_sysfs_unregister_hctxs(q); } - prev_nr_hw_queues = set->nr_hw_queues; if (blk_mq_realloc_tag_set_tags(set, nr_hw_queues) < 0) goto reregister; @@ -4781,6 +4778,10 @@ static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, list_for_each_entry(q, &set->tag_list, tag_set_list) blk_mq_unfreeze_queue(q); + + /* Free the excess tags when nr_hw_queues shrink. */ + for (i = set->nr_hw_queues; i < prev_nr_hw_queues; i++) + __blk_mq_free_map_and_rqs(set, i); } void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues)