Re: [Security] [PATCH 2/2] taskstats: restrict access to user

[Linus Torvalds]

On Mon, Sep 19, 2011 at 11:29 AM, Andi Kleen <andi@xxxxxxxxxxxxxx> wrote:
>>
>>  #define KB 1024
>
> Needs to be 1024ULL, because the counters are 64bit.
>
>>  #define MB (1024*KB)
>> +#define KB_MASK (~(KB-1))
>
> Otherwise you lose the upper 32bits here.

No, it's an "int" constant, so it will sign-extend properly when it
gets extended to 64 bits.

It's "unsigned int" etc that can be dangerous in these kinds of situations.

(Of course, in other contexts, sign-extensions of masks is *bad*. So
it depends on what you do)

                     Linus
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