Re: [PATCH] scsi: libfc: Fix use after free in fc_exch_abts_resp()

[Hannes Reinecke]

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@xxxxxxx>
> ---
>   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@xxxxxxx>

Cheers,

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