[PATCH v2][next] UAPI: ndctl / acpi: intel: Avoid multiple -Wflex-array-member-not-at-end warnings
From: Gustavo A. R. Silva
Date: Thu Feb 13 2025 - 19:53:22 EST
-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@xxxxxxxxxx>
---
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