| Message ID | 20240518182923.1217111-1-linux@roeck-us.net (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] drm/nouveau/nvif: Avoid build error due to potential integer overflows | expand |
On Sat, May 18, 2024 at 11:29:23AM -0700, 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. > > Fixes: a61ddb4393ad ("drm: enable (most) W=1 warnings by default across the subsystem") > Cc: Javier Martinez Canillas <javierm@redhat.com> > Cc: Jani Nikula <jani.nikula@intel.com> > Cc: Thomas Zimmermann <tzimmermann@suse.de> > Cc: Danilo Krummrich <dakr@redhat.com> > Cc: Maxime Ripard <mripard@kernel.org> > Cc: Kees Cook <keescook@chromium.org> > Cc: Christophe JAILLET <christophe.jaillet@wanadoo.fr> > Signed-off-by: Guenter Roeck <linux@roeck-us.net> Yeah, looks good to me. Thanks! Reviewed-by: Kees Cook <keescook@chromium.org>
diff --git a/drivers/gpu/drm/nouveau/nvif/object.c b/drivers/gpu/drm/nouveau/nvif/object.c index 4d1aaee8fe15..89a812f812af 100644 --- a/drivers/gpu/drm/nouveau/nvif/object.c +++ b/drivers/gpu/drm/nouveau/nvif/object.c @@ -142,11 +142,15 @@ 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)) { + if (!(args = kmalloc(args_size, GFP_KERNEL))) return -ENOMEM; } else { args = (void *)stack; @@ -157,7 +161,7 @@ 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 +280,14 @@ 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; + } + + if (!(args = kmalloc(args_size, GFP_KERNEL))) { nvif_object_dtor(object); return -ENOMEM; } @@ -293,8 +304,7 @@ 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)
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. Fixes: a61ddb4393ad ("drm: enable (most) W=1 warnings by default across the subsystem") Cc: Javier Martinez Canillas <javierm@redhat.com> Cc: Jani Nikula <jani.nikula@intel.com> Cc: Thomas Zimmermann <tzimmermann@suse.de> Cc: Danilo Krummrich <dakr@redhat.com> Cc: Maxime Ripard <mripard@kernel.org> Cc: Kees Cook <keescook@chromium.org> Cc: Christophe JAILLET <christophe.jaillet@wanadoo.fr> Signed-off-by: Guenter Roeck <linux@roeck-us.net> --- v2: Use check_add_overflow() to calculate the allocation size and to check for overflows. drivers/gpu/drm/nouveau/nvif/object.c | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-)