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Avoid divide-by-zero when dhcp-range is a whole /64

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This commit is contained in:
Simon Kelley
2016-02-13 17:47:17 +00:00
parent a18bf3149a
commit fdc97e1383
2 changed files with 17 additions and 5 deletions
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5
CHANGELOG
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@@ -43,7 +43,10 @@ version 2.76
Add --add-cpe-id option.
Don't crash with divide-by-zero if an IPv6 dhcp-range
is declared as a whole /64.
(ie xx::0 to xx::ffff:ffff:ffff:ffff)
Thanks to Laurent Bendel for spotting this problem.
version 2.75

11
src/dhcp6.c
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@@ -434,7 +434,16 @@ struct dhcp_context *address6_allocate(struct dhcp_context *context, unsigned c
/* seed is largest extant lease addr in this context */
start = lease_find_max_addr6(c) + serial;
else
start = addr6part(&c->start6) + ((j + c->addr_epoch) % (1 + addr6part(&c->end6) - addr6part(&c->start6)));
{
u64 range = 1 + addr6part(&c->end6) - addr6part(&c->start6);
u64 offset = j + c->addr_epoch;
/* don't divide by zero if range is whole 2^64 */
if (range != 0)
offset = offset % range;
start = addr6part(&c->start6) + offset;
}
/* iterate until we find a free address. */
addr = start;