Re: [PATCH] drm/nouveau/nvif: Avoid build error due to potential integer overflows

[Guenter Roeck]

On 5/18/24 18:19, Joe Perches wrote:
> On Sat, 2024-05-18 at 11:23 -0700, Guenter Roeck wrote:
> > On 5/18/24 10:32, Kees Cook wrote:
> []
> > > I think the INT_MAX test is actually better in this case because
> > > nvif_object_ioctl()'s size argument is u32:
> > >
> > > ret = nvif_object_ioctl(object, args, sizeof(*args) + size, NULL);
> > >                                         ^^^^^^^^^^^^^^^^^^^^
> > >
> > > So that could wrap around, even though the allocation may not.
> > >
> > > Better yet, since "sizeof(*args) + size" is repeated 3 times in the
> > > function, I'd recommend:
> > >
> > > 	...
> > > 	u32 args_size;
> > >
> > > 	if (check_add_overflow(sizeof(*args), size, &args_size))
> > > 		return -ENOMEM;
> > > 	if (args_size > sizeof(stack)) {
> > > 		if (!(args = kmalloc(args_size, GFP_KERNEL)))
>
> trivia:
>
> More typical kernel style would use separate alloc and test
>
> 		args = kmalloc(args_size, GFP_KERNEL);
> 		if (!args)

Sure, I can do that as well. I'll wait a couple of days though before
sending v3 in case there are more change requests.

Guenter