Re: [PATCH net] ptp: Ensure info->enable callback is always set

Thomas Weißschuh
2025-01-22T21:40:57Z

On 2025-01-22 21:15:50+0100, Andrew Lunn wrote:
> On Wed, Jan 22, 2025 at 07:39:31PM +0100, Thomas Weißschuh wrote:
> > The ioctl and sysfs handlers unconditionally call the ->enable callback.
> > Not all drivers implement that callback, leading to NULL dereferences.
> > Example of affected drivers: ptp_s390.c, ptp_vclock.c and ptp_mock.c.
>
> > + if (!ptp->info->enable)
> > + ptp->info->enable = ptp_enable;
>
> Is it possible that a driver has defined info as a const, and placed
> it into read only memory? It is generally good practice to make
> structures of ops read only to prevent some forms of attack.

The modified info struct is a subsystem-private copy and not the struct
passed by the driver. Also ptp_clock_register() requires a mutable
ops struct parameter anyways.