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

[kensanya <kensanya@163.com>]

At 2026-07-23 17:51:20, "Leon Romanovsky" <leon@kernel.org> wrote:
>On Thu, Jul 23, 2026 at 10:44:56AM +0800, kensanya@163.com wrote:
>> From: TanZheng <tanzheng@kylinos.cn>
>> 
>> 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/20260717025402.64054-1-kensanya@163.com/
>> Suggested-by: Bart Van Assche <bvanassche@acm.org>
>> Signed-off-by: TanZheng <tanzheng@kylinos.cn>
>> ---
>> 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.

      I will modify and resend the patch.

>2. You are hardcoding dir, while it can be overwritten in srpt_get_desc_tbl().

      In the srpt_handle_cmd() function:
      &send_ioctx->cmd;
      srpt_get_desc_tbl(..., send_ioctx, ...) 
           ioctx->cmd.data_direction = *dir;

     Therefore, after successfully calling srpt_get_desc_tbl(), even if target_init_cmd() is
     passed DMA_NONE, cmd->data_direction should already have stored the actual direction.

     Do you mean  that after calling srpt_get_desc_tbl(), displaying the overwritten content
     would be better？I want to make sure I address the intent of your comment correctly.
>
>Thanks

Thanks,
TanZheng