netdev - Re: [PATCH net] net/smc: Remove validation of reserved bits in CLC Decline message

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Message-ID: <aLHAAy-S_1_Ud7l-@linux.alibaba.com>
Date: Fri, 29 Aug 2025 22:58:11 +0800
From: Dust Li <dust.li@...ux.alibaba.com>
To: Mahanta Jambigi <mjambigi@...ux.ibm.com>, andrew+netdev@...n.ch,
	davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
	pabeni@...hat.com, alibuda@...ux.alibaba.com, sidraya@...ux.ibm.com,
	wenjia@...ux.ibm.com
Cc: pasic@...ux.ibm.com, horms@...nel.org, tonylu@...ux.alibaba.com,
	guwen@...ux.alibaba.com, netdev@...r.kernel.org,
	linux-s390@...r.kernel.org, linux-rdma@...r.kernel.org,
	Alexandra Winter <wintera@...ux.ibm.com>
Subject: Re: [PATCH net] net/smc: Remove validation of reserved bits in CLC
 Decline message

On 2025-08-29 12:26:26, Mahanta Jambigi wrote:
>Currently SMC code is validating the reserved bits while parsing the incoming
>CLC decline message & when this validation fails, its treated as a protocol
>error. As a result, the SMC connection is terminated instead of falling back to
>TCP. As per RFC7609[1] specs we shouldn't be validating the reserved bits that
>is part of CLC message. This patch fixes this issue.
>
>CLC Decline message format can viewed here[2].
>
>[1] https://datatracker.ietf.org/doc/html/rfc7609#page-92
>[2] https://datatracker.ietf.org/doc/html/rfc7609#page-105
>
>Fixes: 8ade200(net/smc: add v2 format of CLC decline message)
>
>Signed-off-by: Mahanta Jambigi <mjambigi@...ux.ibm.com>
>Reference-ID: LTC214332

I think this is your internal ID ? It's better not to leave that
in the upstream patches.

>Reviewed-by: Sidraya Jayagond <sidraya@...ux.ibm.com>
>Reviewed-by: Alexandra Winter <wintera@...ux.ibm.com>
>
>---
> net/smc/smc_clc.c | 2 --
> 1 file changed, 2 deletions(-)
>
>diff --git a/net/smc/smc_clc.c b/net/smc/smc_clc.c
>index 5a4db151fe95..08be56dfb3f2 100644
>--- a/net/smc/smc_clc.c
>+++ b/net/smc/smc_clc.c
>@@ -426,8 +426,6 @@ smc_clc_msg_decl_valid(struct smc_clc_msg_decline *dclc)
> {
> 	struct smc_clc_msg_hdr *hdr = &dclc->hdr;
> 
>-	if (hdr->typev1 != SMC_TYPE_R && hdr->typev1 != SMC_TYPE_D)
>-		return false;

Here it's checking the typev1 in smc_clc_msg_hdr, but your commit message
says it's validating the reserved bits:

  Currently SMC code is validating the reserved bits while parsing the incoming
  CLC decline message & when this validation fails, its treated as a protocol
  error.

Did I miss something ?

Best regards,
Dust