From: D. Wythe Date: Fri, 7 Nov 2025 02:40:29 +0000 (+0800) Subject: net/smc: fix mismatch between CLC header and proposal X-Git-Tag: v6.18-rc6~31^2~17 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=ec33f2e5a2d0dbbfd71435209aee812fdc9369b8;p=thirdparty%2Flinux.git net/smc: fix mismatch between CLC header and proposal The current CLC proposal message construction uses a mix of `ini->smc_type_v1/v2` and `pclc_base->hdr.typev1/v2` to decide whether to include optional extensions (IPv6 prefix extension for v1, and v2 extension). This leads to a critical inconsistency: when `smc_clc_prfx_set()` fails - for example, in IPv6-only environments with only link-local addresses, or when the local IP address and the outgoing interface’s network address are not in the same subnet. As a result, the proposal message is assembled using the stale `ini->smc_type_v1` value—causing the IPv6 prefix extension to be included even though the header indicates v1 is not supported. The peer then receives a malformed CLC proposal where the header type does not match the payload, and immediately resets the connection. The fix ensures consistency between the CLC header flags and the actual payload by synchronizing `ini->smc_type_v1` with `pclc_base->hdr.typev1` when prefix setup fails. Fixes: 8c3dca341aea ("net/smc: build and send V2 CLC proposal") Signed-off-by: D. Wythe Reviewed-by: Alexandra Winter Link: https://patch.msgid.link/20251107024029.88753-1-alibuda@linux.alibaba.com Signed-off-by: Jakub Kicinski --- diff --git a/net/smc/smc_clc.c b/net/smc/smc_clc.c index 157aace169d49..87c87edadde71 100644 --- a/net/smc/smc_clc.c +++ b/net/smc/smc_clc.c @@ -890,6 +890,7 @@ int smc_clc_send_proposal(struct smc_sock *smc, struct smc_init_info *ini) return SMC_CLC_DECL_CNFERR; } pclc_base->hdr.typev1 = SMC_TYPE_N; + ini->smc_type_v1 = SMC_TYPE_N; } else { pclc_base->iparea_offset = htons(sizeof(*pclc_smcd)); plen += sizeof(*pclc_prfx) +