Re: [PATCH 05/12] firmware: dmi-id: add a release callback function

Nathan Chancellor
2024-03-29T16:12:11Z

On Fri, Mar 29, 2024 at 01:49:17PM +0100, Jean Delvare wrote:
> Hi Arnd,
>
> On Tue, 26 Mar 2024 15:51:30 +0100, Arnd Bergmann wrote:
> > From: Arnd Bergmann <arnd@arndb.de>
> >
> > dmi_class uses kfree() as the .release function, but that now causes
> > a warning with clang-16 as it violates control flow integrity (KCFI)
> > rules:
> >
> > drivers/firmware/dmi-id.c:174:17: error: cast from 'void (*)(const void *)' to 'void (*)(struct device *)' converts to incompatible function type [-Werror,-Wcast-function-type-strict]
> > 174 | .dev_release = (void(*)(struct device *)) kfree,
> >
> > Add an explicit function to call kfree() instead.
> >
> > Fixes: 4f5c791a850e ("DMI-based module autoloading")
>
> Not sure if this fixes tag is really warranted. As I understand it,
> your change only removes a warning but there was no actual bug, right?

Sort of, the warning is really pointing out that calling this callback
will result in a crash at runtime when the kernel is built with kCFI
enabled, which I would consider a bug.

Cheers,
Nathan