linux-kernel - Re: [PATCH] block: blk_init_allocated_queue() set q->fq as NULL in the fail case

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Date:   Mon, 30 Jul 2018 08:28:49 -0600
From:   Jens Axboe <axboe@...nel.dk>
To:     xiao jin <jin.xiao@...el.com>, linux-block@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     tom.leiming@...il.com, bart.vanassche@....com,
        stable@...r.kernel.org, yanmin.zhang@...el.com,
        Ming Lei <ming.lei@...hat.com>
Subject: Re: [PATCH] block: blk_init_allocated_queue() set q->fq as NULL in
 the fail case

On 7/30/18 12:11 AM, xiao jin 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
> blk_init_allocated_queue().

Applied, thanks.

-- 
Jens Axboe