On 03/29/2016 03:06 PM, Vlastimil Babka wrote:
On 03/25/2016 08:22 PM, Andrew Morton wrote:
Also, mm/mempolicy.c:offset_il_node() worries me:
do {
nid = next_node(nid, pol->v.nodes);
c++;
} while (c <= target);
Can't `nid' hit MAX_NUMNODES?
AFAICS it can. interleave_nid() uses this and the nid is then used e.g.
in node_zonelist() where it's used for NODE_DATA(nid). That's quite
scary. It also predates git. Why don't we see crashes or KASAN finding this?
Ah, I see. In offset_il_node(), nid is initialized to -1, and the number
of do-while iterations calling next_node() is up to the number of bits
set in the pol->v.nodes bitmap, so it can't reach past the last set bit
and return MAX_NUMNODES.
