Re: [PATCH -next v2] blk-throttle: Set BIO_THROTTLED when bio has been throttled

[Ming Lei]

On Tue, Mar 01, 2022 at 08:39:19PM +0800, Laibin Qiu wrote:
> 1.In current process, all bio will set the BIO_THROTTLED flag
> after __blk_throtl_bio().
> 
> 2.If bio needs to be throttled, it will start the timer and
> stop submit bio directly. Bio will submit in
> blk_throtl_dispatch_work_fn() when the timer expires.But in
> the current process, if bio is throttled. The BIO_THROTTLED
> will be set to bio after timer start. If the bio has been
> completed, it may cause use-after-free blow.
> 
> BUG: KASAN: use-after-free in blk_throtl_bio+0x12f0/0x2c70
> Read of size 2 at addr ffff88801b8902d4 by task fio/26380

After the queue lock is released, the bio can be dispatched & completed,
so it shouldn't be touched after lock release:

Reviewed-by: Ming Lei <ming.lei@xxxxxxxxxx>

Thanks,
Ming