Re: net: Zeroing the structure ethtool_wolinfo in ethtool_get_wol()

[Andrey Ryabinin]

2016-08-23 18:36 GMT+03:00 Eric Dumazet <eric.dumazet@xxxxxxxxx>:
> On Tue, 2016-08-23 at 08:05 -0700, Joe Perches wrote:
>
>> A compiler does not have a standards based requirement to
>> initialize arbitrary padding bytes.
>>
>> I believe gcc always does zero all padding anyway.
>
> I would not worry for kernel code, because the amount of scrutiny there
> will be enough to 'fix potential bugs' [1], but a lot of user land code
> would suffer from various bugs as well that might sit there forever.
>
> [1] Also, most call sites in the kernel are using same call stack, so
> the offset of '1-7 leaked bytes' vs kernel stack is constant, making
> exploits quite challenging.
>
> Even if the current standards are lazy (are they, I did not check ?),
> security needs would call for a sane compiler behavior and changing the
> standards accordingly.
>

 C11 guarantees zeroed padding.