Re: [PATCH] nouveau/gsp: Avoid addressing beyond end of rpc->entries

[Danilo Krummrich]

On 3/30/24 15:12, Kees Cook wrote:

Using the end of rpc->entries[] for addressing runs into both compile-time
and run-time detection of accessing beyond the end of the array. Use the
base pointer instead, since was allocated with the additional bytes for
storing the strings. Avoids the following warning in future GCC releases
with support for __counted_by:

In function 'fortify_memcpy_chk',
 inlined from 'r535_gsp_rpc_set_registry' at 
../drivers/gpu/drm/nouveau/nvkm/subdev/gsp/r535.c:1123:3:
../include/linux/fortify-string.h:553:25: error: call to 
'__write_overflow_field' declared with attribute warning: detected write beyond 
size of field (1st parameter); maybe use struct_group()? 
[-Werror=attribute-warning]
   553 | __write_overflow_field(p_size_field, size);
   | ^~

for this code:

strings = (char *)>entries[NV_GSP_REG_NUM_ENTRIES];
...
 memcpy(strings, r535_registry_entries[i].name, name_len);

Signed-off-by: Kees Cook 


Applied to drm-misc-fixes, thanks!


---
Cc: Karol Herbst 
Cc: Lyude Paul 
Cc: Danilo Krummrich 
Cc: David Airlie 
Cc: Daniel Vetter 
Cc: Dave Airlie 
Cc: Ben Skeggs 
Cc: Timur Tabi 
Cc: dri-de...@lists.freedesktop.org
Cc: nouveau@lists.freedesktop.org
---
  drivers/gpu/drm/nouveau/nvkm/subdev/gsp/r535.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/r535.c 
b/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/r535.c
index 9994cbd6f1c4..9858c1438aa7 100644
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/r535.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/r535.c
@@ -1112,7 +1112,7 @@ r535_gsp_rpc_set_registry(struct nvkm_gsp *gsp)
rpc->numEntries = NV_GSP_REG_NUM_ENTRIES;
  
  	str_offset = offsetof(typeof(*rpc), entries[NV_GSP_REG_NUM_ENTRIES]);

-   strings = (char *)>entries[NV_GSP_REG_NUM_ENTRIES];
+   strings = (char *)rpc + str_offset;
for (i = 0; i < NV_GSP_REG_NUM_ENTRIES; i++) {
int name_len = strlen(r535_registry_entries[i].name) + 1;
  

[PATCH] nouveau/gsp: Avoid addressing beyond end of rpc->entries

[Kees Cook]

Using the end of rpc->entries[] for addressing runs into both compile-time
and run-time detection of accessing beyond the end of the array. Use the
base pointer instead, since was allocated with the additional bytes for
storing the strings. Avoids the following warning in future GCC releases
with support for __counted_by:

In function 'fortify_memcpy_chk',
inlined from 'r535_gsp_rpc_set_registry' at 
../drivers/gpu/drm/nouveau/nvkm/subdev/gsp/r535.c:1123:3:
../include/linux/fortify-string.h:553:25: error: call to 
'__write_overflow_field' declared with attribute warning: detected write beyond 
size of field (1st parameter); maybe use struct_group()? 
[-Werror=attribute-warning]
  553 | __write_overflow_field(p_size_field, size);
  | ^~

for this code:

strings = (char *)>entries[NV_GSP_REG_NUM_ENTRIES];
...
memcpy(strings, r535_registry_entries[i].name, name_len);

Signed-off-by: Kees Cook 
---
Cc: Karol Herbst 
Cc: Lyude Paul 
Cc: Danilo Krummrich 
Cc: David Airlie 
Cc: Daniel Vetter 
Cc: Dave Airlie 
Cc: Ben Skeggs 
Cc: Timur Tabi 
Cc: dri-de...@lists.freedesktop.org
Cc: nouveau@lists.freedesktop.org
---
 drivers/gpu/drm/nouveau/nvkm/subdev/gsp/r535.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/r535.c 
b/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/r535.c
index 9994cbd6f1c4..9858c1438aa7 100644
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/r535.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/r535.c
@@ -1112,7 +1112,7 @@ r535_gsp_rpc_set_registry(struct nvkm_gsp *gsp)
rpc->numEntries = NV_GSP_REG_NUM_ENTRIES;
 
str_offset = offsetof(typeof(*rpc), entries[NV_GSP_REG_NUM_ENTRIES]);
-   strings = (char *)>entries[NV_GSP_REG_NUM_ENTRIES];
+   strings = (char *)rpc + str_offset;
for (i = 0; i < NV_GSP_REG_NUM_ENTRIES; i++) {
int name_len = strlen(r535_registry_entries[i].name) + 1;
 
-- 
2.34.1