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Message-ID: <51943e86-e05c-8f3c-59de-e75af03a1efe@suse.de>
Date:   Thu, 3 Mar 2022 08:26:03 +0100
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Subject: Re: [PATCH] scsi: libfc: Fix use after free in fc_exch_abts_resp()
Content-Language: en-US
To:     Jianglei Nie <niejianglei2021@163.com>, jejb@linux.ibm.com,
        martin.petersen@oracle.com
Cc:     linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20220303015115.459778-1-niejianglei2021@163.com>
From:   Hannes Reinecke <hare@suse.de>
In-Reply-To: <20220303015115.459778-1-niejianglei2021@163.com>
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On 3/3/22 02:51, Jianglei Nie wrote:
> fc_exch_release(ep) will decrease the ep's reference count. When the
> reference count reaches zero, it is freed. But ep is still used in the
> following code, which will lead to a use after free.
> 
> We should return the function after the call of fc_exch_release() to
> avoid use after free.
> 
> Signed-off-by: Jianglei Nie <niejianglei2021@163.com>
> ---
>   drivers/scsi/libfc/fc_exch.c | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/scsi/libfc/fc_exch.c b/drivers/scsi/libfc/fc_exch.c
> index 841000445b9a..aa223db4cf53 100644
> --- a/drivers/scsi/libfc/fc_exch.c
> +++ b/drivers/scsi/libfc/fc_exch.c
> @@ -1701,6 +1701,7 @@ static void fc_exch_abts_resp(struct fc_exch *ep, struct fc_frame *fp)
>   	if (cancel_delayed_work_sync(&ep->timeout_work)) {
>   		FC_EXCH_DBG(ep, "Exchange timer canceled due to ABTS response\n");
>   		fc_exch_release(ep);	/* release from pending timer hold */
> +		return;
>   	}
>   
>   	spin_lock_bh(&ep->ex_lock);

Reviewed-by: Hannes Reinecke <hare@suse.de>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                Kernel Storage Architect
hare@suse.de                              +49 911 74053 688
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