Re: [PATCH] blk-mq: fix tags UAF when shrink nr_hw_queues

[Hannes Reinecke <hare@suse.de>]

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
-- 
Dr. Hannes Reinecke                Kernel Storage Architect
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