[PATCH] powerpc/legacy_serial: Fix UBSAN: array-index-out-of-bounds

[Christophe Leroy]

Le 11/05/2021 à 03:16, Michael Ellerman a écrit :
> Segher Boessenkool <segher at kernel.crashing.org> writes:
> 
>> On Sat, May 08, 2021 at 06:36:21AM +0000, Christophe Leroy wrote:
>>> UBSAN complains when a pointer is calculated with invalid
>>> 'legacy_serial_console' index, allthough the index is verified
>>> before dereferencing the pointer.
>>
>> Addressing like this is UB already.
>>
>> You could just move this:
>>
>>> -	if (legacy_serial_console < 0)
>>> -		return 0;
>>
>> to before
>>
>>> -	struct legacy_serial_info *info = &legacy_serial_infos[legacy_serial_console];
>>> -	struct plat_serial8250_port *port = &legacy_serial_ports[legacy_serial_console];
>>
>> and no other change is necessary.
> 
> Yeah I sent a v2 doing that, thanks.
> 

I wanted something looking similar to setup_legacy_serial_console(), but of course this also works.

Christophe