2024-03-30 14:12:17

by Kees Cook

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

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 *)&rpc->entries[NV_GSP_REG_NUM_ENTRIES];
...
memcpy(strings, r535_registry_entries[i].name, name_len);

Signed-off-by: Kees Cook <[email protected]>
---
Cc: Karol Herbst <[email protected]>
Cc: Lyude Paul <[email protected]>
Cc: Danilo Krummrich <[email protected]>
Cc: David Airlie <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: Dave Airlie <[email protected]>
Cc: Ben Skeggs <[email protected]>
Cc: Timur Tabi <[email protected]>
Cc: [email protected]
Cc: [email protected]
---
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 *)&rpc->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

2024-04-05 16:37:51

by Danilo Krummrich

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

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 *)&rpc->entries[NV_GSP_REG_NUM_ENTRIES];
> ...
> memcpy(strings, r535_registry_entries[i].name, name_len);
>
> Signed-off-by: Kees Cook <[email protected]>

Applied to drm-misc-fixes, thanks!

> ---
> Cc: Karol Herbst <[email protected]>
> Cc: Lyude Paul <[email protected]>
> Cc: Danilo Krummrich <[email protected]>
> Cc: David Airlie <[email protected]>
> Cc: Daniel Vetter <[email protected]>
> Cc: Dave Airlie <[email protected]>
> Cc: Ben Skeggs <[email protected]>
> Cc: Timur Tabi <[email protected]>
> Cc: [email protected]
> Cc: [email protected]
> ---
> 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 *)&rpc->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;
>