[PATCH] IB/srp: Never use immediate data if it is disabled by a user

[PATCH] IB/srp: Never use immediate data if it is disabled by a user

[Sergey Gorenko]

Some SRP targets that do not support specification SRP-2, put
the garbage to the reserved bits of the SRP login response.
The problem was not detected for a long time because the SRP
initiator ignored those bits. But now one of them is used as
SRP_LOGIN_RSP_IMMED_SUPP. And it causes a critical error on
the target when the initiator sends immediate data.

The ib_srp module has a use_imm_date parameter to enable or
disable immediate data manually. But it does not help in the above
case, because use_imm_date is ignored at handling the SRP login
response. The problem is definitely caused by a bug on the target
side, but the initiator's behavior also does not look correct.
The initiator should not use immediate data if use_imm_date is
disabled by a user.

This commit adds an additional checking of use_imm_date at
the handling of SRP login response to avoid unexpected use of
immediate data.

Fixes: commit 882981f4a411 ("RDMA/srp: Add support for immediate data")
Signed-off-by: Sergey Gorenko <sergeygo@mellanox.com>
---
 drivers/infiniband/ulp/srp/ib_srp.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c
index b7f7a5f7bd98..cd1181c39ed2 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.c
+++ b/drivers/infiniband/ulp/srp/ib_srp.c
@@ -2546,7 +2546,8 @@ static void srp_cm_rep_handler(struct ib_cm_id *cm_id,
 	if (lrsp->opcode == SRP_LOGIN_RSP) {
 		ch->max_ti_iu_len = be32_to_cpu(lrsp->max_ti_iu_len);
 		ch->req_lim       = be32_to_cpu(lrsp->req_lim_delta);
-		ch->use_imm_data  = lrsp->rsp_flags & SRP_LOGIN_RSP_IMMED_SUPP;
+		ch->use_imm_data  = srp_use_imm_data &&
+			(lrsp->rsp_flags & SRP_LOGIN_RSP_IMMED_SUPP);
 		ch->max_it_iu_len = srp_max_it_iu_len(target->cmd_sg_cnt,
 						      ch->use_imm_data,
 						      target->max_it_iu_size);
-- 
2.21.0

Re: [PATCH] IB/srp: Never use immediate data if it is disabled by a user

[Bart Van Assche]

On 1/15/20 5:30 AM, Sergey Gorenko wrote:
> Some SRP targets that do not support specification SRP-2, put
> the garbage to the reserved bits of the SRP login response.
> The problem was not detected for a long time because the SRP
> initiator ignored those bits. But now one of them is used as
> SRP_LOGIN_RSP_IMMED_SUPP. And it causes a critical error on
> the target when the initiator sends immediate data.
> 
> The ib_srp module has a use_imm_date parameter to enable or
> disable immediate data manually. But it does not help in the above
> case, because use_imm_date is ignored at handling the SRP login
> response. The problem is definitely caused by a bug on the target
> side, but the initiator's behavior also does not look correct.
> The initiator should not use immediate data if use_imm_date is
> disabled by a user.
> 
> This commit adds an additional checking of use_imm_date at
> the handling of SRP login response to avoid unexpected use of
> immediate data.

Reviewed-by: Bart Van Assche <bvanassche@acm.org>

Re: [PATCH] IB/srp: Never use immediate data if it is disabled by a user

[Jason Gunthorpe]

On Wed, Jan 15, 2020 at 01:30:55PM +0000, Sergey Gorenko wrote:
> Some SRP targets that do not support specification SRP-2, put
> the garbage to the reserved bits of the SRP login response.
> The problem was not detected for a long time because the SRP
> initiator ignored those bits. But now one of them is used as
> SRP_LOGIN_RSP_IMMED_SUPP. And it causes a critical error on
> the target when the initiator sends immediate data.
> 
> The ib_srp module has a use_imm_date parameter to enable or
> disable immediate data manually. But it does not help in the above
> case, because use_imm_date is ignored at handling the SRP login
> response. The problem is definitely caused by a bug on the target
> side, but the initiator's behavior also does not look correct.
> The initiator should not use immediate data if use_imm_date is
> disabled by a user.
> 
> This commit adds an additional checking of use_imm_date at
> the handling of SRP login response to avoid unexpected use of
> immediate data.
> 
> Fixes: commit 882981f4a411 ("RDMA/srp: Add support for immediate data")
> Signed-off-by: Sergey Gorenko <sergeygo@mellanox.com>
> Reviewed-by: Bart Van Assche <bvanassche@acm.org>
> ---
>  drivers/infiniband/ulp/srp/ib_srp.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)

Applied to for-next, thanks

Jason