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authorChengming Zhou <zhouchengming@bytedance.com>2023-09-08 03:57:02 +0300
committerJens Axboe <axboe@kernel.dk>2023-09-12 01:17:34 +0300
commit6be6d112419713334ddd9c01f219ca16adaa4c76 (patch)
tree18d2b39d8bd624ce27fa3779e95860aed42db0b0 /block
parent0bb80ecc33a8fb5a682236443c1e740d5c917d1d (diff)
downloadlinux-6be6d112419713334ddd9c01f219ca16adaa4c76.tar.xz
blk-mq: fix tags UAF when shrinking q->nr_hw_queues
When nr_hw_queues shrink, we free the excess tags before realloc'ing hw_ctxs for each queue. During that resize, we may need to access those tags, like blk_mq_tag_idle(hctx) will access queue shared tags. This can cause a slab use-after-free, as 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> Reviewed-by: Hannes Reinecke <hare@suse.de> Link: https://lore.kernel.org/r/20230908005702.2183908-1-chengming.zhou@linux.dev Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
-rw-r--r--block/blk-mq.c13
1 files changed, 7 insertions, 6 deletions
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 @@ switch_back:
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)