On Thu, Sep 14, 2023 at 09:30:37PM +0000, Justin Stitt wrote: > `strncpy` is deprecated and as such we should prefer more robust and > less ambiguous string interfaces. > > A suitable replacement is `strscpy_pad` due to the fact that it > guarantees NUL-termination on the destination buffer whilst also > maintaining the NUL-padding behavior that `strncpy` provides. I am not > sure whether NUL-padding is strictly needed but I see in > `nvif_object_ctor()` args is memcpy'd elsewhere so I figured we'd keep > the same functionality. > > Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1] > Link: https://github.com/KSPP/linux/issues/90 > Cc: linux-hardening@xxxxxxxxxxxxxxx > Signed-off-by: Justin Stitt <justinstitt@xxxxxxxxxx> > --- > Note: build-tested only. > --- > drivers/gpu/drm/nouveau/nvif/client.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/nouveau/nvif/client.c b/drivers/gpu/drm/nouveau/nvif/client.c > index a3264a0e933a..3a27245f467f 100644 > --- a/drivers/gpu/drm/nouveau/nvif/client.c > +++ b/drivers/gpu/drm/nouveau/nvif/client.c > @@ -69,7 +69,7 @@ nvif_client_ctor(struct nvif_client *parent, const char *name, u64 device, > } nop = {}; > int ret; > > - strncpy(args.name, name, sizeof(args.name)); > + strscpy_pad(args.name, name, sizeof(args.name)); > ret = nvif_object_ctor(parent != client ? &parent->object : NULL, > name ? name : "nvifClient", 0, > NVIF_CLASS_CLIENT, &args, sizeof(args), Right, I see the memcpy too: nvif_object_ctor(struct nvif_object *parent, const char *name, u32 handle, s32 oclass, void *data, u32 size, struct nvif_object *object) { ... memcpy(args->new.data, data, size); However, "args" is already zeroed: struct nvif_client_v0 args = { .device = device }; So there's no need for _pad(). However, I couldn't immediatley see why args.name must be %NUL terminated. It's ultimately passed through an ioctl: return client->driver->ioctl(client->object.priv, data, size, hack); But I did find it... args is: struct nvif_client_v0 { ... char name[32]; }; And "name" only ever comes through nvif_client_ctor(), which all end up via here, using "cli": struct nouveau_cli { ... char name[32]; ... snprintf(cli->name, sizeof(cli->name), "%s", sname); ... ret = nvif_client_ctor(&drm->master.base, cli->name, device, &cli->base); So we'll always be %NUL terminated. Therefore, yes, conversion looks good: Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx> Thanks! -Kees > > --- > base-commit: 3669558bdf354cd352be955ef2764cde6a9bf5ec > change-id: 20230914-strncpy-drivers-gpu-drm-nouveau-nvif-client-c-82b023c36953 > > Best regards, > -- > Justin Stitt <justinstitt@xxxxxxxxxx> > -- Kees Cook
