On 2017/10/31 17:30, Vlastimil Babka wrote:
> On 10/27/2017 12:14 PM, Yisheng Xie wrote:
>> + /*
>> + * When the user specified more nodes than supported just check
>> + * if the non supported part is all zero.
>> + *
>> + * If maxnode have more longs than MAX_NUMNODES, check
>> + * the bits in that area first. And then go through to
>> + * check the rest bits which equal or bigger than MAX_NUMNODES.
>> + * Otherwise, just check bits [MAX_NUMNODES, maxnode).
>> + */
>> if (nlongs > BITS_TO_LONGS(MAX_NUMNODES)) {
>> for (k = BITS_TO_LONGS(MAX_NUMNODES); k < nlongs; k++) {
>> - unsigned long t;
>> if (get_user(t, nmask + k))
>> return -EFAULT;
>> if (k == nlongs - 1) {
>> @@ -1294,6 +1301,16 @@ static int get_nodes(nodemask_t *nodes, const unsigned long __user *nmask,
>> endmask = ~0UL;
>> }
>>
>> + if (maxnode > MAX_NUMNODES && MAX_NUMNODES % BITS_PER_LONG != 0) {
>> + unsigned long valid_mask = endmask;
>> +
>> + valid_mask &= ~((1UL << (MAX_NUMNODES % BITS_PER_LONG)) - 1);
>
> I'm not sure if the combination with endmask works in this case:
>
> 0 BITS_PER_LONG 2xBITS_PER_LONG
> |____________|____________|
> | |
> MAX_NUMNODES maxnode
>
> endmask will contain bits between 0 and maxnode
In the case, BITS_TO_LONGS(maxnode) > BITS_TO_LONGS(MAX_NUMNODES), right?
And after checking BITS_PER_LONG to 2xBITS_PER_LONG，endmask will set to
"~0UL". e.g. endmask will be 0xffff ffff ffff ffff if
unsigned long is 64bit.
Then the valid_mask will just contain bits MAX_NUMNODES to BITS_PER_LONG.
Thanks
Yisheng Xie
> but here we want to check bits between MAX_NUMNODES and BITS_PER_LONG
> and endmask should not be mixed up with that?
>
>
> Vlastimil
>
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