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

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

[kensanya]

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);
+	if (rc != 0) {
+		pr_debug("target_init_cmd() returned %d for tag %#llx\n", rc,
+			 srp_cmd->tag);
+		target_free_tag(ch->sess, cmd);
+		return;
+	}
+
 	rc = srpt_get_desc_tbl(recv_ioctx, send_ioctx, srp_cmd, &dir,
 			       &sg, &sg_cnt, &data_len, ch->imm_data_offset);
 	if (rc) {
@@ -1594,14 +1613,11 @@ static void srpt_handle_cmd(struct srpt_rdma_ch *ch,
 		goto busy;
 	}
 
-	rc = target_init_cmd(cmd, ch->sess, &send_ioctx->sense_data[0],
-			     scsilun_to_int(&srp_cmd->lun), data_len,
-			     TCM_SIMPLE_TAG, dir, TARGET_SCF_ACK_KREF);
-	if (rc != 0) {
-		pr_debug("target_submit_cmd() returned %d for tag %#llx\n", rc,
-			 srp_cmd->tag);
-		goto busy;
-	}
+	/*
+	 * Replace the placeholder length from target_init_cmd(). Direction
+	 * was already set inside srpt_get_desc_tbl() for srpt_alloc_rw_ctxs().
+	 */
+	cmd->data_length = data_len;
 
 	if (target_submit_prep(cmd, srp_cmd->cdb, sg, sg_cnt, NULL, 0, NULL, 0,
 			       GFP_KERNEL))
-- 
2.25.1

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

[Leon Romanovsky]

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

Thanks

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

[kensanya]

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

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

[Leon Romanovsky]

On Fri, Jul 24, 2026 at 10:42:53AM +0800, kensanya wrote:
> 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.

You need to do this correctly: target_init_cmd() must receive the
correct directory, as calculated by srpt_get_desc_tbl().

Thanks

> >
> >Thanks
> 
> Thanks,
> TanZheng