net/smc: Avoid -Wflex-array-member-not-at-end warnings

-Wflex-array-member-not-at-end is coming in GCC-14, and we are getting
ready to enable it globally.

There are currently a couple of objects in `struct smc_clc_msg_proposal_area`
that contain a couple of flexible structures:

struct smc_clc_msg_proposal_area {
	...
	struct smc_clc_v2_extension             pclc_v2_ext;
	...
	struct smc_clc_smcd_v2_extension        pclc_smcd_v2_ext;
	...
};

So, in order to avoid ending up with a couple of flexible-array members
in the middle of a struct, we use the `struct_group_tagged()` helper to
separate the flexible array from the rest of the members in the flexible
structure:

struct smc_clc_smcd_v2_extension {
        struct_group_tagged(smc_clc_smcd_v2_extension_fixed, fixed,
                            u8 system_eid[SMC_MAX_EID_LEN];
                            u8 reserved[16];
        );
        struct smc_clc_smcd_gid_chid gidchid[];
};

With the change described above, we now declare objects of the type of
the tagged struct without embedding flexible arrays in the middle of
another struct:

struct smc_clc_msg_proposal_area {
        ...
        struct smc_clc_v2_extension_fixed	pclc_v2_ext;
        ...
        struct smc_clc_smcd_v2_extension_fixed	pclc_smcd_v2_ext;
        ...
};

We also use `container_of()` when we need to retrieve a pointer to the
flexible structures.

So, with these changes, fix the following warnings:

In file included from net/smc/af_smc.c:42:
net/smc/smc_clc.h:186:49: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
  186 |         struct smc_clc_v2_extension             pclc_v2_ext;
      |                                                 ^~~~~~~~~~~
net/smc/smc_clc.h:188:49: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
  188 |         struct smc_clc_smcd_v2_extension        pclc_smcd_v2_ext;
      |                                                 ^~~~~~~~~~~~~~~~

Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Reviewed-by: Wen Gu <guwen@linux.alibaba.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/smc/smc_clc.c b/net/smc/smc_clc.c
index e55026c7529cf8ea41b96202735d0e8a5539f0e2..33fa787c28ebb2f63e4b9c163ff357e24dab9079 100644 (file)
--- a/net/smc/smc_clc.c
+++ b/net/smc/smc_clc.c
@@ -853,8 +853,10 @@ int smc_clc_send_proposal(struct smc_sock *smc, struct smc_init_info *ini)
        pclc_smcd = &pclc->pclc_smcd;
        pclc_prfx = &pclc->pclc_prfx;
        ipv6_prfx = pclc->pclc_prfx_ipv6;
-       v2_ext = &pclc->pclc_v2_ext;
-       smcd_v2_ext = &pclc->pclc_smcd_v2_ext;
+       v2_ext = container_of(&pclc->pclc_v2_ext,
+                             struct smc_clc_v2_extension, fixed);
+       smcd_v2_ext = container_of(&pclc->pclc_smcd_v2_ext,
+                                  struct smc_clc_smcd_v2_extension, fixed);
        gidchids = pclc->pclc_gidchids;
        trl = &pclc->pclc_trl;
 

diff --git a/net/smc/smc_clc.h b/net/smc/smc_clc.h
index 7cc7070b9772de621f55af972071c4700790922c..467effb50cd65789c61da846de681687aedc41d6 100644 (file)
--- a/net/smc/smc_clc.h
+++ b/net/smc/smc_clc.h
@@ -134,12 +134,15 @@ struct smc_clc_smcd_gid_chid {
                         */
 
 struct smc_clc_v2_extension {
-       struct smc_clnt_opts_area_hdr hdr;
-       u8 roce[16];            /* RoCEv2 GID */
-       u8 max_conns;
-       u8 max_links;
-       __be16 feature_mask;
-       u8 reserved[12];
+       /* New members must be added within the struct_group() macro below. */
+       struct_group_tagged(smc_clc_v2_extension_fixed, fixed,
+               struct smc_clnt_opts_area_hdr hdr;
+               u8 roce[16];            /* RoCEv2 GID */
+               u8 max_conns;
+               u8 max_links;
+               __be16 feature_mask;
+               u8 reserved[12];
+       );
        u8 user_eids[][SMC_MAX_EID_LEN];
 };
 
@@ -159,8 +162,11 @@ struct smc_clc_msg_smcd {  /* SMC-D GID information */
 };
 
 struct smc_clc_smcd_v2_extension {
-       u8 system_eid[SMC_MAX_EID_LEN];
-       u8 reserved[16];
+       /* New members must be added within the struct_group() macro below. */
+       struct_group_tagged(smc_clc_smcd_v2_extension_fixed, fixed,
+               u8 system_eid[SMC_MAX_EID_LEN];
+               u8 reserved[16];
+       );
        struct smc_clc_smcd_gid_chid gidchid[];
 };
 
@@ -183,9 +189,9 @@ struct smc_clc_msg_proposal_area {
        struct smc_clc_msg_smcd                 pclc_smcd;
        struct smc_clc_msg_proposal_prefix      pclc_prfx;
        struct smc_clc_ipv6_prefix      pclc_prfx_ipv6[SMC_CLC_MAX_V6_PREFIX];
-       struct smc_clc_v2_extension             pclc_v2_ext;
+       struct smc_clc_v2_extension_fixed       pclc_v2_ext;
        u8                      user_eids[SMC_CLC_MAX_UEID][SMC_MAX_EID_LEN];
-       struct smc_clc_smcd_v2_extension        pclc_smcd_v2_ext;
+       struct smc_clc_smcd_v2_extension_fixed  pclc_smcd_v2_ext;
        struct smc_clc_smcd_gid_chid
                                pclc_gidchids[SMCD_CLC_MAX_V2_GID_ENTRIES];
        struct smc_clc_msg_trail                pclc_trl;