| Message ID | Z66T8tSKjVutr6of@kspp (mailing list archive) |
|---|---|
| State | Handled Elsewhere, archived |
| Headers | show |
| Series | [v2,next] UAPI: ndctl / acpi: intel: Avoid multiple -Wflex-array-member-not-at-end warnings | expand |
On Fri, Feb 14, 2025 at 11:23:06AM +1030, Gustavo A. R. Silva wrote: > -Wflex-array-member-not-at-end was introduced in GCC-14, and we are > getting ready to enable it, globally. > > So, in order to avoid ending up with flexible-array members in the > middle of other structs, we use the `__struct_group()` helper to > separate the flexible array from the rest of the members in the > flexible structure. We then use the newly created tagged `struct > nd_cmd_pkg_hdr` to replace the type of the objects causing trouble: > `pkg` in multiple structs. > > Below is the before-and-after changes of the memory layout in `struct > nd_cmd_pkg`. This to illustrate that the use of `__struct_group()` > doesn't alter the layout, ensuring that user space remains unaffected. > > Before changes: > struct nd_cmd_pkg { > __u64 nd_family; /* 0 8 */ > __u64 nd_command; /* 8 8 */ > __u32 nd_size_in; /* 16 4 */ > __u32 nd_size_out; /* 20 4 */ > __u32 nd_reserved2[9]; /* 24 36 */ > __u32 nd_fw_size; /* 60 4 */ > /* --- cacheline 1 boundary (64 bytes) --- */ > unsigned char nd_payload[]; /* 64 0 */ > > /* size: 64, cachelines: 1, members: 7 */ > }; > > After changes: > struct nd_cmd_pkg { > union { > struct { > __u64 nd_family; /* 0 8 */ > __u64 nd_command; /* 8 8 */ > __u32 nd_size_in; /* 16 4 */ > __u32 nd_size_out; /* 20 4 */ > __u32 nd_reserved2[9]; /* 24 36 */ > __u32 nd_fw_size; /* 60 4 */ > }; /* 0 64 */ > struct nd_cmd_pkg_hdr __hdr; /* 0 64 */ > }; /* 0 64 */ > /* --- cacheline 1 boundary (64 bytes) --- */ > unsigned char nd_payload[]; /* 64 0 */ > > /* size: 64, cachelines: 1, members: 2 */ > }; > > It's also worth mentioning that all members of the struct can still be > accessed directly, for example instance->nd_family, instance->nd_command, > and so on. > > So, with these changes, fix 12 of the following warnings: > > drivers/acpi/nfit/intel.c:692:35: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end] > > Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> Reviewed-by: Alison Schofield <alison.schofield@intel.com> > --- > Changes in v2: > - Show changes in UAPI first. (Alison) > - Update changelog text --add more information about _struct_group() > changes. (Alison) > > v1: > - Link: https://lore.kernel.org/linux-hardening/Z618ILbAR8YAvTkd@kspp/ > > include/uapi/linux/ndctl.h | 15 +++++++++------ > drivers/acpi/nfit/intel.c | 24 ++++++++++++------------ > 2 files changed, 21 insertions(+), 18 deletions(-) > > diff --git a/include/uapi/linux/ndctl.h b/include/uapi/linux/ndctl.h > index 73516e263627..34c11644d5d7 100644 > --- a/include/uapi/linux/ndctl.h > +++ b/include/uapi/linux/ndctl.h > @@ -227,12 +227,15 @@ enum ars_masks { > */ > > struct nd_cmd_pkg { > - __u64 nd_family; /* family of commands */ > - __u64 nd_command; > - __u32 nd_size_in; /* INPUT: size of input args */ > - __u32 nd_size_out; /* INPUT: size of payload */ > - __u32 nd_reserved2[9]; /* reserved must be zero */ > - __u32 nd_fw_size; /* OUTPUT: size fw wants to return */ > + /* New members MUST be added within the __struct_group() macro below. */ > + __struct_group(nd_cmd_pkg_hdr, __hdr, /* no attrs */, > + __u64 nd_family; /* family of commands */ > + __u64 nd_command; > + __u32 nd_size_in; /* INPUT: size of input args */ > + __u32 nd_size_out; /* INPUT: size of payload */ > + __u32 nd_reserved2[9]; /* reserved must be zero */ > + __u32 nd_fw_size; /* OUTPUT: size fw wants to return */ > + ); > unsigned char nd_payload[]; /* Contents of call */ > }; > > diff --git a/drivers/acpi/nfit/intel.c b/drivers/acpi/nfit/intel.c > index 3902759abcba..fe561ce0ddec 100644 > --- a/drivers/acpi/nfit/intel.c > +++ b/drivers/acpi/nfit/intel.c > @@ -56,7 +56,7 @@ static unsigned long intel_security_flags(struct nvdimm *nvdimm, > struct nfit_mem *nfit_mem = nvdimm_provider_data(nvdimm); > unsigned long security_flags = 0; > struct { > - struct nd_cmd_pkg pkg; > + struct nd_cmd_pkg_hdr pkg; > struct nd_intel_get_security_state cmd; > } nd_cmd = { > .pkg = { > @@ -121,7 +121,7 @@ static int intel_security_freeze(struct nvdimm *nvdimm) > { > struct nfit_mem *nfit_mem = nvdimm_provider_data(nvdimm); > struct { > - struct nd_cmd_pkg pkg; > + struct nd_cmd_pkg_hdr pkg; > struct nd_intel_freeze_lock cmd; > } nd_cmd = { > .pkg = { > @@ -154,7 +154,7 @@ static int intel_security_change_key(struct nvdimm *nvdimm, > NVDIMM_INTEL_SET_MASTER_PASSPHRASE : > NVDIMM_INTEL_SET_PASSPHRASE; > struct { > - struct nd_cmd_pkg pkg; > + struct nd_cmd_pkg_hdr pkg; > struct nd_intel_set_passphrase cmd; > } nd_cmd = { > .pkg = { > @@ -196,7 +196,7 @@ static int __maybe_unused intel_security_unlock(struct nvdimm *nvdimm, > { > struct nfit_mem *nfit_mem = nvdimm_provider_data(nvdimm); > struct { > - struct nd_cmd_pkg pkg; > + struct nd_cmd_pkg_hdr pkg; > struct nd_intel_unlock_unit cmd; > } nd_cmd = { > .pkg = { > @@ -235,7 +235,7 @@ static int intel_security_disable(struct nvdimm *nvdimm, > int rc; > struct nfit_mem *nfit_mem = nvdimm_provider_data(nvdimm); > struct { > - struct nd_cmd_pkg pkg; > + struct nd_cmd_pkg_hdr pkg; > struct nd_intel_disable_passphrase cmd; > } nd_cmd = { > .pkg = { > @@ -278,7 +278,7 @@ static int __maybe_unused intel_security_erase(struct nvdimm *nvdimm, > unsigned int cmd = ptype == NVDIMM_MASTER ? > NVDIMM_INTEL_MASTER_SECURE_ERASE : NVDIMM_INTEL_SECURE_ERASE; > struct { > - struct nd_cmd_pkg pkg; > + struct nd_cmd_pkg_hdr pkg; > struct nd_intel_secure_erase cmd; > } nd_cmd = { > .pkg = { > @@ -319,7 +319,7 @@ static int __maybe_unused intel_security_query_overwrite(struct nvdimm *nvdimm) > int rc; > struct nfit_mem *nfit_mem = nvdimm_provider_data(nvdimm); > struct { > - struct nd_cmd_pkg pkg; > + struct nd_cmd_pkg_hdr pkg; > struct nd_intel_query_overwrite cmd; > } nd_cmd = { > .pkg = { > @@ -355,7 +355,7 @@ static int __maybe_unused intel_security_overwrite(struct nvdimm *nvdimm, > int rc; > struct nfit_mem *nfit_mem = nvdimm_provider_data(nvdimm); > struct { > - struct nd_cmd_pkg pkg; > + struct nd_cmd_pkg_hdr pkg; > struct nd_intel_overwrite cmd; > } nd_cmd = { > .pkg = { > @@ -408,7 +408,7 @@ static int intel_bus_fwa_businfo(struct nvdimm_bus_descriptor *nd_desc, > struct nd_intel_bus_fw_activate_businfo *info) > { > struct { > - struct nd_cmd_pkg pkg; > + struct nd_cmd_pkg_hdr pkg; > struct nd_intel_bus_fw_activate_businfo cmd; > } nd_cmd = { > .pkg = { > @@ -519,7 +519,7 @@ static int intel_bus_fwa_activate(struct nvdimm_bus_descriptor *nd_desc) > { > struct acpi_nfit_desc *acpi_desc = to_acpi_desc(nd_desc); > struct { > - struct nd_cmd_pkg pkg; > + struct nd_cmd_pkg_hdr pkg; > struct nd_intel_bus_fw_activate cmd; > } nd_cmd = { > .pkg = { > @@ -583,7 +583,7 @@ static int intel_fwa_dimminfo(struct nvdimm *nvdimm, > struct nd_intel_fw_activate_dimminfo *info) > { > struct { > - struct nd_cmd_pkg pkg; > + struct nd_cmd_pkg_hdr pkg; > struct nd_intel_fw_activate_dimminfo cmd; > } nd_cmd = { > .pkg = { > @@ -689,7 +689,7 @@ static int intel_fwa_arm(struct nvdimm *nvdimm, enum nvdimm_fwa_trigger arm) > struct nfit_mem *nfit_mem = nvdimm_provider_data(nvdimm); > struct acpi_nfit_desc *acpi_desc = nfit_mem->acpi_desc; > struct { > - struct nd_cmd_pkg pkg; > + struct nd_cmd_pkg_hdr pkg; > struct nd_intel_fw_activate_arm cmd; > } nd_cmd = { > .pkg = { > -- > 2.43.0 >
On 2/13/25 5:53 PM, Gustavo A. R. Silva wrote: > -Wflex-array-member-not-at-end was introduced in GCC-14, and we are > getting ready to enable it, globally. > > So, in order to avoid ending up with flexible-array members in the > middle of other structs, we use the `__struct_group()` helper to > separate the flexible array from the rest of the members in the > flexible structure. We then use the newly created tagged `struct > nd_cmd_pkg_hdr` to replace the type of the objects causing trouble: > `pkg` in multiple structs. > > Below is the before-and-after changes of the memory layout in `struct > nd_cmd_pkg`. This to illustrate that the use of `__struct_group()` > doesn't alter the layout, ensuring that user space remains unaffected. > > Before changes: > struct nd_cmd_pkg { > __u64 nd_family; /* 0 8 */ > __u64 nd_command; /* 8 8 */ > __u32 nd_size_in; /* 16 4 */ > __u32 nd_size_out; /* 20 4 */ > __u32 nd_reserved2[9]; /* 24 36 */ > __u32 nd_fw_size; /* 60 4 */ > /* --- cacheline 1 boundary (64 bytes) --- */ > unsigned char nd_payload[]; /* 64 0 */ > > /* size: 64, cachelines: 1, members: 7 */ > }; > > After changes: > struct nd_cmd_pkg { > union { > struct { > __u64 nd_family; /* 0 8 */ > __u64 nd_command; /* 8 8 */ > __u32 nd_size_in; /* 16 4 */ > __u32 nd_size_out; /* 20 4 */ > __u32 nd_reserved2[9]; /* 24 36 */ > __u32 nd_fw_size; /* 60 4 */ > }; /* 0 64 */ > struct nd_cmd_pkg_hdr __hdr; /* 0 64 */ > }; /* 0 64 */ > /* --- cacheline 1 boundary (64 bytes) --- */ > unsigned char nd_payload[]; /* 64 0 */ > > /* size: 64, cachelines: 1, members: 2 */ > }; > > It's also worth mentioning that all members of the struct can still be > accessed directly, for example instance->nd_family, instance->nd_command, > and so on. > > So, with these changes, fix 12 of the following warnings: > > drivers/acpi/nfit/intel.c:692:35: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end] > > Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> Reviewed-by: Dave Jiang <dave.jiang@intel.com> > --- > Changes in v2: > - Show changes in UAPI first. (Alison) > - Update changelog text --add more information about _struct_group() > changes. (Alison) > > v1: > - Link: https://lore.kernel.org/linux-hardening/Z618ILbAR8YAvTkd@kspp/ > > include/uapi/linux/ndctl.h | 15 +++++++++------ > drivers/acpi/nfit/intel.c | 24 ++++++++++++------------ > 2 files changed, 21 insertions(+), 18 deletions(-) > > diff --git a/include/uapi/linux/ndctl.h b/include/uapi/linux/ndctl.h > index 73516e263627..34c11644d5d7 100644 > --- a/include/uapi/linux/ndctl.h > +++ b/include/uapi/linux/ndctl.h > @@ -227,12 +227,15 @@ enum ars_masks { > */ > > struct nd_cmd_pkg { > - __u64 nd_family; /* family of commands */ > - __u64 nd_command; > - __u32 nd_size_in; /* INPUT: size of input args */ > - __u32 nd_size_out; /* INPUT: size of payload */ > - __u32 nd_reserved2[9]; /* reserved must be zero */ > - __u32 nd_fw_size; /* OUTPUT: size fw wants to return */ > + /* New members MUST be added within the __struct_group() macro below. */ > + __struct_group(nd_cmd_pkg_hdr, __hdr, /* no attrs */, > + __u64 nd_family; /* family of commands */ > + __u64 nd_command; > + __u32 nd_size_in; /* INPUT: size of input args */ > + __u32 nd_size_out; /* INPUT: size of payload */ > + __u32 nd_reserved2[9]; /* reserved must be zero */ > + __u32 nd_fw_size; /* OUTPUT: size fw wants to return */ > + ); > unsigned char nd_payload[]; /* Contents of call */ > }; > > diff --git a/drivers/acpi/nfit/intel.c b/drivers/acpi/nfit/intel.c > index 3902759abcba..fe561ce0ddec 100644 > --- a/drivers/acpi/nfit/intel.c > +++ b/drivers/acpi/nfit/intel.c > @@ -56,7 +56,7 @@ static unsigned long intel_security_flags(struct nvdimm *nvdimm, > struct nfit_mem *nfit_mem = nvdimm_provider_data(nvdimm); > unsigned long security_flags = 0; > struct { > - struct nd_cmd_pkg pkg; > + struct nd_cmd_pkg_hdr pkg; > struct nd_intel_get_security_state cmd; > } nd_cmd = { > .pkg = { > @@ -121,7 +121,7 @@ static int intel_security_freeze(struct nvdimm *nvdimm) > { > struct nfit_mem *nfit_mem = nvdimm_provider_data(nvdimm); > struct { > - struct nd_cmd_pkg pkg; > + struct nd_cmd_pkg_hdr pkg; > struct nd_intel_freeze_lock cmd; > } nd_cmd = { > .pkg = { > @@ -154,7 +154,7 @@ static int intel_security_change_key(struct nvdimm *nvdimm, > NVDIMM_INTEL_SET_MASTER_PASSPHRASE : > NVDIMM_INTEL_SET_PASSPHRASE; > struct { > - struct nd_cmd_pkg pkg; > + struct nd_cmd_pkg_hdr pkg; > struct nd_intel_set_passphrase cmd; > } nd_cmd = { > .pkg = { > @@ -196,7 +196,7 @@ static int __maybe_unused intel_security_unlock(struct nvdimm *nvdimm, > { > struct nfit_mem *nfit_mem = nvdimm_provider_data(nvdimm); > struct { > - struct nd_cmd_pkg pkg; > + struct nd_cmd_pkg_hdr pkg; > struct nd_intel_unlock_unit cmd; > } nd_cmd = { > .pkg = { > @@ -235,7 +235,7 @@ static int intel_security_disable(struct nvdimm *nvdimm, > int rc; > struct nfit_mem *nfit_mem = nvdimm_provider_data(nvdimm); > struct { > - struct nd_cmd_pkg pkg; > + struct nd_cmd_pkg_hdr pkg; > struct nd_intel_disable_passphrase cmd; > } nd_cmd = { > .pkg = { > @@ -278,7 +278,7 @@ static int __maybe_unused intel_security_erase(struct nvdimm *nvdimm, > unsigned int cmd = ptype == NVDIMM_MASTER ? > NVDIMM_INTEL_MASTER_SECURE_ERASE : NVDIMM_INTEL_SECURE_ERASE; > struct { > - struct nd_cmd_pkg pkg; > + struct nd_cmd_pkg_hdr pkg; > struct nd_intel_secure_erase cmd; > } nd_cmd = { > .pkg = { > @@ -319,7 +319,7 @@ static int __maybe_unused intel_security_query_overwrite(struct nvdimm *nvdimm) > int rc; > struct nfit_mem *nfit_mem = nvdimm_provider_data(nvdimm); > struct { > - struct nd_cmd_pkg pkg; > + struct nd_cmd_pkg_hdr pkg; > struct nd_intel_query_overwrite cmd; > } nd_cmd = { > .pkg = { > @@ -355,7 +355,7 @@ static int __maybe_unused intel_security_overwrite(struct nvdimm *nvdimm, > int rc; > struct nfit_mem *nfit_mem = nvdimm_provider_data(nvdimm); > struct { > - struct nd_cmd_pkg pkg; > + struct nd_cmd_pkg_hdr pkg; > struct nd_intel_overwrite cmd; > } nd_cmd = { > .pkg = { > @@ -408,7 +408,7 @@ static int intel_bus_fwa_businfo(struct nvdimm_bus_descriptor *nd_desc, > struct nd_intel_bus_fw_activate_businfo *info) > { > struct { > - struct nd_cmd_pkg pkg; > + struct nd_cmd_pkg_hdr pkg; > struct nd_intel_bus_fw_activate_businfo cmd; > } nd_cmd = { > .pkg = { > @@ -519,7 +519,7 @@ static int intel_bus_fwa_activate(struct nvdimm_bus_descriptor *nd_desc) > { > struct acpi_nfit_desc *acpi_desc = to_acpi_desc(nd_desc); > struct { > - struct nd_cmd_pkg pkg; > + struct nd_cmd_pkg_hdr pkg; > struct nd_intel_bus_fw_activate cmd; > } nd_cmd = { > .pkg = { > @@ -583,7 +583,7 @@ static int intel_fwa_dimminfo(struct nvdimm *nvdimm, > struct nd_intel_fw_activate_dimminfo *info) > { > struct { > - struct nd_cmd_pkg pkg; > + struct nd_cmd_pkg_hdr pkg; > struct nd_intel_fw_activate_dimminfo cmd; > } nd_cmd = { > .pkg = { > @@ -689,7 +689,7 @@ static int intel_fwa_arm(struct nvdimm *nvdimm, enum nvdimm_fwa_trigger arm) > struct nfit_mem *nfit_mem = nvdimm_provider_data(nvdimm); > struct acpi_nfit_desc *acpi_desc = nfit_mem->acpi_desc; > struct { > - struct nd_cmd_pkg pkg; > + struct nd_cmd_pkg_hdr pkg; > struct nd_intel_fw_activate_arm cmd; > } nd_cmd = { > .pkg = {
diff --git a/include/uapi/linux/ndctl.h b/include/uapi/linux/ndctl.h index 73516e263627..34c11644d5d7 100644 --- a/include/uapi/linux/ndctl.h +++ b/include/uapi/linux/ndctl.h @@ -227,12 +227,15 @@ enum ars_masks { */ struct nd_cmd_pkg { - __u64 nd_family; /* family of commands */ - __u64 nd_command; - __u32 nd_size_in; /* INPUT: size of input args */ - __u32 nd_size_out; /* INPUT: size of payload */ - __u32 nd_reserved2[9]; /* reserved must be zero */ - __u32 nd_fw_size; /* OUTPUT: size fw wants to return */ + /* New members MUST be added within the __struct_group() macro below. */ + __struct_group(nd_cmd_pkg_hdr, __hdr, /* no attrs */, + __u64 nd_family; /* family of commands */ + __u64 nd_command; + __u32 nd_size_in; /* INPUT: size of input args */ + __u32 nd_size_out; /* INPUT: size of payload */ + __u32 nd_reserved2[9]; /* reserved must be zero */ + __u32 nd_fw_size; /* OUTPUT: size fw wants to return */ + ); unsigned char nd_payload[]; /* Contents of call */ }; diff --git a/drivers/acpi/nfit/intel.c b/drivers/acpi/nfit/intel.c index 3902759abcba..fe561ce0ddec 100644 --- a/drivers/acpi/nfit/intel.c +++ b/drivers/acpi/nfit/intel.c @@ -56,7 +56,7 @@ static unsigned long intel_security_flags(struct nvdimm *nvdimm, struct nfit_mem *nfit_mem = nvdimm_provider_data(nvdimm); unsigned long security_flags = 0; struct { - struct nd_cmd_pkg pkg; + struct nd_cmd_pkg_hdr pkg; struct nd_intel_get_security_state cmd; } nd_cmd = { .pkg = { @@ -121,7 +121,7 @@ static int intel_security_freeze(struct nvdimm *nvdimm) { struct nfit_mem *nfit_mem = nvdimm_provider_data(nvdimm); struct { - struct nd_cmd_pkg pkg; + struct nd_cmd_pkg_hdr pkg; struct nd_intel_freeze_lock cmd; } nd_cmd = { .pkg = { @@ -154,7 +154,7 @@ static int intel_security_change_key(struct nvdimm *nvdimm, NVDIMM_INTEL_SET_MASTER_PASSPHRASE : NVDIMM_INTEL_SET_PASSPHRASE; struct { - struct nd_cmd_pkg pkg; + struct nd_cmd_pkg_hdr pkg; struct nd_intel_set_passphrase cmd; } nd_cmd = { .pkg = { @@ -196,7 +196,7 @@ static int __maybe_unused intel_security_unlock(struct nvdimm *nvdimm, { struct nfit_mem *nfit_mem = nvdimm_provider_data(nvdimm); struct { - struct nd_cmd_pkg pkg; + struct nd_cmd_pkg_hdr pkg; struct nd_intel_unlock_unit cmd; } nd_cmd = { .pkg = { @@ -235,7 +235,7 @@ static int intel_security_disable(struct nvdimm *nvdimm, int rc; struct nfit_mem *nfit_mem = nvdimm_provider_data(nvdimm); struct { - struct nd_cmd_pkg pkg; + struct nd_cmd_pkg_hdr pkg; struct nd_intel_disable_passphrase cmd; } nd_cmd = { .pkg = { @@ -278,7 +278,7 @@ static int __maybe_unused intel_security_erase(struct nvdimm *nvdimm, unsigned int cmd = ptype == NVDIMM_MASTER ? NVDIMM_INTEL_MASTER_SECURE_ERASE : NVDIMM_INTEL_SECURE_ERASE; struct { - struct nd_cmd_pkg pkg; + struct nd_cmd_pkg_hdr pkg; struct nd_intel_secure_erase cmd; } nd_cmd = { .pkg = { @@ -319,7 +319,7 @@ static int __maybe_unused intel_security_query_overwrite(struct nvdimm *nvdimm) int rc; struct nfit_mem *nfit_mem = nvdimm_provider_data(nvdimm); struct { - struct nd_cmd_pkg pkg; + struct nd_cmd_pkg_hdr pkg; struct nd_intel_query_overwrite cmd; } nd_cmd = { .pkg = { @@ -355,7 +355,7 @@ static int __maybe_unused intel_security_overwrite(struct nvdimm *nvdimm, int rc; struct nfit_mem *nfit_mem = nvdimm_provider_data(nvdimm); struct { - struct nd_cmd_pkg pkg; + struct nd_cmd_pkg_hdr pkg; struct nd_intel_overwrite cmd; } nd_cmd = { .pkg = { @@ -408,7 +408,7 @@ static int intel_bus_fwa_businfo(struct nvdimm_bus_descriptor *nd_desc, struct nd_intel_bus_fw_activate_businfo *info) { struct { - struct nd_cmd_pkg pkg; + struct nd_cmd_pkg_hdr pkg; struct nd_intel_bus_fw_activate_businfo cmd; } nd_cmd = { .pkg = { @@ -519,7 +519,7 @@ static int intel_bus_fwa_activate(struct nvdimm_bus_descriptor *nd_desc) { struct acpi_nfit_desc *acpi_desc = to_acpi_desc(nd_desc); struct { - struct nd_cmd_pkg pkg; + struct nd_cmd_pkg_hdr pkg; struct nd_intel_bus_fw_activate cmd; } nd_cmd = { .pkg = { @@ -583,7 +583,7 @@ static int intel_fwa_dimminfo(struct nvdimm *nvdimm, struct nd_intel_fw_activate_dimminfo *info) { struct { - struct nd_cmd_pkg pkg; + struct nd_cmd_pkg_hdr pkg; struct nd_intel_fw_activate_dimminfo cmd; } nd_cmd = { .pkg = { @@ -689,7 +689,7 @@ static int intel_fwa_arm(struct nvdimm *nvdimm, enum nvdimm_fwa_trigger arm) struct nfit_mem *nfit_mem = nvdimm_provider_data(nvdimm); struct acpi_nfit_desc *acpi_desc = nfit_mem->acpi_desc; struct { - struct nd_cmd_pkg pkg; + struct nd_cmd_pkg_hdr pkg; struct nd_intel_fw_activate_arm cmd; } nd_cmd = { .pkg = {
-Wflex-array-member-not-at-end was introduced in GCC-14, and we are getting ready to enable it, globally. So, in order to avoid ending up with flexible-array members in the middle of other structs, we use the `__struct_group()` helper to separate the flexible array from the rest of the members in the flexible structure. We then use the newly created tagged `struct nd_cmd_pkg_hdr` to replace the type of the objects causing trouble: `pkg` in multiple structs. Below is the before-and-after changes of the memory layout in `struct nd_cmd_pkg`. This to illustrate that the use of `__struct_group()` doesn't alter the layout, ensuring that user space remains unaffected. Before changes: struct nd_cmd_pkg { __u64 nd_family; /* 0 8 */ __u64 nd_command; /* 8 8 */ __u32 nd_size_in; /* 16 4 */ __u32 nd_size_out; /* 20 4 */ __u32 nd_reserved2[9]; /* 24 36 */ __u32 nd_fw_size; /* 60 4 */ /* --- cacheline 1 boundary (64 bytes) --- */ unsigned char nd_payload[]; /* 64 0 */ /* size: 64, cachelines: 1, members: 7 */ }; After changes: struct nd_cmd_pkg { union { struct { __u64 nd_family; /* 0 8 */ __u64 nd_command; /* 8 8 */ __u32 nd_size_in; /* 16 4 */ __u32 nd_size_out; /* 20 4 */ __u32 nd_reserved2[9]; /* 24 36 */ __u32 nd_fw_size; /* 60 4 */ }; /* 0 64 */ struct nd_cmd_pkg_hdr __hdr; /* 0 64 */ }; /* 0 64 */ /* --- cacheline 1 boundary (64 bytes) --- */ unsigned char nd_payload[]; /* 64 0 */ /* size: 64, cachelines: 1, members: 2 */ }; It's also worth mentioning that all members of the struct can still be accessed directly, for example instance->nd_family, instance->nd_command, and so on. So, with these changes, fix 12 of the following warnings: drivers/acpi/nfit/intel.c:692:35: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end] Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> --- Changes in v2: - Show changes in UAPI first. (Alison) - Update changelog text --add more information about _struct_group() changes. (Alison) v1: - Link: https://lore.kernel.org/linux-hardening/Z618ILbAR8YAvTkd@kspp/ include/uapi/linux/ndctl.h | 15 +++++++++------ drivers/acpi/nfit/intel.c | 24 ++++++++++++------------ 2 files changed, 21 insertions(+), 18 deletions(-)