On 5/24/24 15:48, Guenter Roeck wrote:
Trying to build parisc:allmodconfig with gcc 12.x or later results
in the following build error.
drivers/gpu/drm/nouveau/nvif/object.c: In function 'nvif_object_mthd':
drivers/gpu/drm/nouveau/nvif/object.c:161:9: error:
'memcpy' accessing 4294967264 or more bytes at offsets 0 and 32 overlaps 6442450881 bytes at offset -2147483617 [-Werror=restrict]
161 | memcpy(data, args->mthd.data, size);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/nouveau/nvif/object.c: In function 'nvif_object_ctor':
drivers/gpu/drm/nouveau/nvif/object.c:298:17: error:
'memcpy' accessing 4294967240 or more bytes at offsets 0 and 56 overlaps 6442450833 bytes at offset -2147483593 [-Werror=restrict]
298 | memcpy(data, args->new.data, size);
gcc assumes that 'sizeof(*args) + size' can overflow, which would result
in the problem.
The problem is not new, only it is now no longer a warning but an error
since W=1 has been enabled for the drm subsystem and since Werror is
enabled for test builds.
Rearrange arithmetic and use check_add_overflow() for validating the
allocation size to avoid the overflow. While at it, split assignments
out of if conditions.
Fixes: a61ddb4393ad ("drm: enable (most) W=1 warnings by default across the subsystem")
Cc: Javier Martinez Canillas <javierm@xxxxxxxxxx>
Cc: Jani Nikula <jani.nikula@xxxxxxxxx>
Cc: Thomas Zimmermann <tzimmermann@xxxxxxx>
Cc: Danilo Krummrich <dakr@xxxxxxxxxx>
Cc: Maxime Ripard <mripard@xxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>
Cc: Joe Perches <joe@xxxxxxxxxxx>
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Applied to drm-misc-fixes, thanks!
---
v3: Split assignments from if conditions.
v2: Use check_add_overflow() to calculate the allocation size and to check
for overflows.
drivers/gpu/drm/nouveau/nvif/object.c | 24 ++++++++++++++++++------
1 file changed, 18 insertions(+), 6 deletions(-)
diff --git a/drivers/gpu/drm/nouveau/nvif/object.c b/drivers/gpu/drm/nouveau/nvif/object.c
index 4d1aaee8fe15..1d19c87eaec1 100644
--- a/drivers/gpu/drm/nouveau/nvif/object.c
+++ b/drivers/gpu/drm/nouveau/nvif/object.c
@@ -142,11 +142,16 @@ nvif_object_mthd(struct nvif_object *object, u32 mthd, void *data, u32 size)
struct nvif_ioctl_v0 ioctl;
struct nvif_ioctl_mthd_v0 mthd;
} *args;
+ u32 args_size;
u8 stack[128];
int ret;
- if (sizeof(*args) + size > sizeof(stack)) {
- if (!(args = kmalloc(sizeof(*args) + size, GFP_KERNEL)))
+ if (check_add_overflow(sizeof(*args), size, &args_size))
+ return -ENOMEM;
+
+ if (args_size > sizeof(stack)) {
+ args = kmalloc(args_size, GFP_KERNEL);
+ if (!args)
return -ENOMEM;
} else {
args = (void *)stack;
@@ -157,7 +162,7 @@ nvif_object_mthd(struct nvif_object *object, u32 mthd, void *data, u32 size)
args->mthd.method = mthd;
memcpy(args->mthd.data, data, size);
- ret = nvif_object_ioctl(object, args, sizeof(*args) + size, NULL);
+ ret = nvif_object_ioctl(object, args, args_size, NULL);
memcpy(data, args->mthd.data, size);
if (args != (void *)stack)
kfree(args);
@@ -276,7 +281,15 @@ nvif_object_ctor(struct nvif_object *parent, const char *name, u32 handle,
object->map.size = 0;
if (parent) {
- if (!(args = kmalloc(sizeof(*args) + size, GFP_KERNEL))) {
+ u32 args_size;
+
+ if (check_add_overflow(sizeof(*args), size, &args_size)) {
+ nvif_object_dtor(object);
+ return -ENOMEM;
+ }
+
+ args = kmalloc(args_size, GFP_KERNEL);
+ if (!args) {
nvif_object_dtor(object);
return -ENOMEM;
}
@@ -293,8 +306,7 @@ nvif_object_ctor(struct nvif_object *parent, const char *name, u32 handle,
args->new.oclass = oclass;
memcpy(args->new.data, data, size);
- ret = nvif_object_ioctl(parent, args, sizeof(*args) + size,
- &object->priv);
+ ret = nvif_object_ioctl(parent, args, args_size, &object->priv);
memcpy(data, args->new.data, size);
kfree(args);
if (ret == 0)
