Re: [PATCH] blk_init_allocated_queue() set q->fq as NULL in the fail case
From: Ming Lei
Date: Sun Jul 29 2018 - 23:58:02 EST
On Mon, Jul 30, 2018 at 10:03 AM, xiao jin <jin.xiao@xxxxxxxxx> wrote:
> We find the memory use-after-free issue in __blk_drain_queue()
> on the kernel 4.14. After read the latest kernel 4.18-rc6 we
> think it has the same problem.
> Memory is allocated for q->fq in the blk_init_allocated_queue().
> If the elevator init function called with error return, it will
> run into the fail case to free the q->fq.
> Then the __blk_drain_queue() uses the same memory after the free
> of the q->fq, it will lead to the unpredictable event.
> The patch is to set q->fq as NULL in the fail case of
> Signed-off-by: xiao jin <jin.xiao@xxxxxxxxx>
> block/blk-core.c | 1 +
> 1 file changed, 1 insertion(+)
> diff --git a/block/blk-core.c b/block/blk-core.c
> index b888175..52635e2 100644
> --- a/block/blk-core.c
> +++ b/block/blk-core.c
> @@ -1072,6 +1072,7 @@ int blk_init_allocated_queue(struct request_queue *q)
> q->exit_rq_fn(q, q->fq->flush_rq);
> + q->fq = NULL;
> return -ENOMEM;
Reviewed-by: Ming Lei <ming.lei@xxxxxxxxxx>