Re: [PATCH 5.8 regression fix] platform/x86: thinkpad_acpi: Revert: Use strndup_user() in dispatch_proc_write()

[Andy Shevchenko]

On Tue, Jul 14, 2020 at 11:15 AM Hans de Goede <hdegoede@xxxxxxxxxx> wrote:
>
> Commit 35d13c7a0512 ("platform/x86: thinkpad_acpi: Use strndup_user()
> in dispatch_proc_write()") cleaned up dispatch_proc_write() by replacing
> the code to copy the passed in data from userspae with strndup_user().

user space

> But strndup_user() expects a 0 terminated input buffer and the buffer
> passed to dispatch_proc_write() is NOT 0 terminated.
>
> So this change leads to strndup_user() copying some extra random bytes
> from userspace till it hits a 0 byte.
>
> This commit reverts the change to use strndup_user() fixing the
> buffer being passed to the ibm_struct.write() call back containing extra
> junk at the end.

Can we simply use memdup_user()?
And thanks for catching this up!

-- 
With Best Regards,
Andy Shevchenko