| Message ID | ZgXmscAd6Y2iQQ6O@neat (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 9748dbc9f26541d35c4231348c64499bf7a19735 |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [v4,next] net/smc: Avoid -Wflex-array-member-not-at-end warnings | expand |
On 2024/3/29 05:52, Gustavo A. R. Silva wrote: > -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> Thank you, Gustavo. Reviewed-by: Wen Gu <guwen@linux.alibaba.com> > --- > Changes v4: > - Fix code comments (due to copy/paste error, aghhh). > > Changes in v3: > - Adjust code to 80 columns. (Wen Gu) > - Add a couple of code comments. > - Link: https://lore.kernel.org/linux-hardening/ZgXlIADfiXSyRz8d@neat/ > > Changes in v2: > - Name the tagged struct *_fixed instead of *_hdr. > - Add Kees' RB tag. > - Link: https://lore.kernel.org/linux-hardening/ZfCXBykRw5XqBvf0@neat/ > > v1: > - Link: https://lore.kernel.org/linux-hardening/ZeIhOT44ON5rjPiP@neat/ > > net/smc/smc_clc.c | 6 ++++-- > net/smc/smc_clc.h | 26 ++++++++++++++++---------- > 2 files changed, 20 insertions(+), 12 deletions(-) > > diff --git a/net/smc/smc_clc.c b/net/smc/smc_clc.c > index e55026c7529c..33fa787c28eb 100644 > --- 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 7cc7070b9772..467effb50cd6 100644 > --- 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;
Hello: This patch was applied to netdev/net-next.git (main) by David S. Miller <davem@davemloft.net>: On Thu, 28 Mar 2024 15:52:49 -0600 you wrote: > -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; > ... > }; > > [...] Here is the summary with links: - [v4,next] net/smc: Avoid -Wflex-array-member-not-at-end warnings https://git.kernel.org/netdev/net-next/c/9748dbc9f265 You are awesome, thank you!
diff --git a/net/smc/smc_clc.c b/net/smc/smc_clc.c index e55026c7529c..33fa787c28eb 100644 --- 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 7cc7070b9772..467effb50cd6 100644 --- 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;
-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> --- Changes v4: - Fix code comments (due to copy/paste error, aghhh). Changes in v3: - Adjust code to 80 columns. (Wen Gu) - Add a couple of code comments. - Link: https://lore.kernel.org/linux-hardening/ZgXlIADfiXSyRz8d@neat/ Changes in v2: - Name the tagged struct *_fixed instead of *_hdr. - Add Kees' RB tag. - Link: https://lore.kernel.org/linux-hardening/ZfCXBykRw5XqBvf0@neat/ v1: - Link: https://lore.kernel.org/linux-hardening/ZeIhOT44ON5rjPiP@neat/ net/smc/smc_clc.c | 6 ++++-- net/smc/smc_clc.h | 26 ++++++++++++++++---------- 2 files changed, 20 insertions(+), 12 deletions(-)