[PATCH][next] nouveau/gsp: replace zero-length array with flex-array member and use __counted_by

Gustavo A. R. Silva
2023-11-16T18:11:51Z

Fake flexible arrays (zero-length and one-element arrays) are deprecated,
and should be replaced by flexible-array members. So, replace
zero-length array with a flexible-array member in `struct
PACKED_REGISTRY_TABLE`.

Also annotate array `entries` with `__counted_by()` to prepare for the
coming implementation by GCC and Clang of the `__counted_by` attribute.
Flexible array members annotated with `__counted_by` can have their
accesses bounds-checked at run-time via `CONFIG_UBSAN_BOUNDS` (for array
indexing) and `CONFIG_FORTIFY_SOURCE` (for strcpy/memcpy-family functions).

This fixes multiple -Warray-bounds warnings:
drivers/gpu/drm/nouveau/nvkm/subdev/gsp/r535.c:1069:29: warning: array subscript 0 is outside array bounds of 'PACKED_REGISTRY_ENTRY[0]' [-Warray-bounds=]
drivers/gpu/drm/nouveau/nvkm/subdev/gsp/r535.c:1070:29: warning: array subscript 0 is outside array bounds of 'PACKED_REGISTRY_ENTRY[0]' [-Warray-bounds=]
drivers/gpu/drm/nouveau/nvkm/subdev/gsp/r535.c:1071:29: warning: array subscript 0 is outside array bounds of 'PACKED_REGISTRY_ENTRY[0]' [-Warray-bounds=]
drivers/gpu/drm/nouveau/nvkm/subdev/gsp/r535.c:1072:29: warning: array subscript 0 is outside array bounds of 'PACKED_REGISTRY_ENTRY[0]' [-Warray-bounds=]

While there, also make use of the struct_size() helper, and address
checkpatch.pl warning:
WARNING: please, no spaces at the start of a line

This results in no differences in binary output.

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
.../nvrm/535.113.01/nvidia/generated/g_os_nvoc.h | 14 +++++++-------
drivers/gpu/drm/nouveau/nvkm/subdev/gsp/r535.c | 2 +-
2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/include/nvrm/535.113.01/nvidia/generated/g_os_nvoc.h b/drivers/gpu/drm/nouveau/include/nvrm/535.113.01/nvidia/generated/g_os_nvoc.h
index 754c6af42f30..259b25c2ac6b 100644
--- a/drivers/gpu/drm/nouveau/include/nvrm/535.113.01/nvidia/generated/g_os_nvoc.h
+++ b/drivers/gpu/drm/nouveau/include/nvrm/535.113.01/nvidia/generated/g_os_nvoc.h
@@ -28,17 +28,17 @@

typedef struct PACKED_REGISTRY_ENTRY
{
- NvU32 nameOffset;
- NvU8 type;
- NvU32 data;
- NvU32 length;
+ NvU32 nameOffset;
+ NvU8 type;
+ NvU32 data;
+ NvU32 length;
} PACKED_REGISTRY_ENTRY;

typedef struct PACKED_REGISTRY_TABLE
{
- NvU32 size;
- NvU32 numEntries;
- PACKED_REGISTRY_ENTRY entries[0];
+ NvU32 size;
+ NvU32 numEntries;
+ PACKED_REGISTRY_ENTRY entries[] __counted_by(numEntries);
} PACKED_REGISTRY_TABLE;

#endif
diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/r535.c b/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/r535.c
index dc44f5c7833f..228335487af5 100644
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/r535.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/r535.c
@@ -1048,7 +1048,7 @@ r535_gsp_rpc_set_registry(struct nvkm_gsp *gsp)
char *strings;
int str_offset;
int i;
- size_t rpc_size = sizeof(*rpc) + sizeof(rpc->entries[0]) * NV_GSP_REG_NUM_ENTRIES;
+ size_t rpc_size = struct_size(rpc, entries, NV_GSP_REG_NUM_ENTRIES);

/* add strings + null terminator */
for (i = 0; i < NV_GSP_REG_NUM_ENTRIES; i++)
--
2.34.1