Re: [PATCH v2] RDMA/srpt: fix NULL deref when sending BUSY before target_init_cmd()

On Thu, Jul 23, 2026 at 10:44:56AM +0800, [email protected] wrote:
> From: TanZheng <[email protected]>
> 
> If srpt_get_desc_tbl() fails, srpt_handle_cmd() jumps to
> target_send_busy() before target_init_cmd() has set cmd->se_tfo.
> target_send_busy() then dereferences a NULL se_tfo.
> 
> Call target_init_cmd() first with placeholder data_length and
> data_direction, parse the descriptor table next, then fill in the
> real data_length. That way target_send_busy() is safe if parsing
> fails.
> 
> target_send_busy() is only valid after a successful target_init_cmd().
> If target_init_cmd() itself fails, free the send ioctx tag locally
> with target_free_tag() instead of calling target_send_busy().
> 
> Fixes: 8b8807b9e982 ("scsi: RDMA/srpt: Fix handling of command / TMF submission failure")
> Link: https://lore.kernel.org/all/[email protected]/
> Suggested-by: Bart Van Assche <[email protected]>
> Signed-off-by: TanZheng <[email protected]>
> ---
> v2:
> - On target_init_cmd() failure, use target_free_tag() instead of
>   target_send_busy()
> 
>  drivers/infiniband/ulp/srpt/ib_srpt.c | 36 +++++++++++++++++++--------
>  1 file changed, 26 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/infiniband/ulp/srpt/ib_srpt.c b/drivers/infiniband/ulp/srpt/ib_srpt.c
> index f66cfd70c263..71af1fb0d380 100644
> --- a/drivers/infiniband/ulp/srpt/ib_srpt.c
> +++ b/drivers/infiniband/ulp/srpt/ib_srpt.c
> @@ -1558,8 +1558,8 @@ static void srpt_handle_cmd(struct srpt_rdma_ch *ch,
>  	struct srp_cmd *srp_cmd;
>  	struct scatterlist *sg = NULL;
>  	unsigned sg_cnt = 0;
> -	u64 data_len;
> -	enum dma_data_direction dir;
> +	u64 data_len = 0;
> +	enum dma_data_direction dir = DMA_NONE;
>  	int rc;
>  
>  	BUG_ON(!send_ioctx);
> @@ -1584,6 +1584,25 @@ static void srpt_handle_cmd(struct srpt_rdma_ch *ch,
>  		break;
>  	}
>  
> +	/*
> +	 * Call target_init_cmd() before srpt_get_desc_tbl() so that
> +	 * cmd->se_tfo is set if descriptor parsing fails and
> +	 * target_send_busy() is used. data_length is filled in after a
> +	 * successful srpt_get_desc_tbl().
> +	 *
> +	 * target_send_busy() is only valid after a successful
> +	 * target_init_cmd(). On init failure free the tag locally.
> +	 */
> +	rc = target_init_cmd(cmd, ch->sess, &send_ioctx->sense_data[0],
> +			     scsilun_to_int(&srp_cmd->lun), 0 /* data_len */,
> +			     TCM_SIMPLE_TAG, DMA_NONE, TARGET_SCF_ACK_KREF);

1. TCM_SIMPLE_TAG -> you need to rebase to latest rdma-next.
2. You are hardcoding dir, while it can be overwritten in srpt_get_desc_tbl().

Thanks