net: ipmr/ip6mr: prevent out-of-bounds vif_table access
When cache is unresolved, c->mf[6]c_parent is set to 65535 and
minvif, maxvif are not initialized, hence we must avoid to
parse IIF and OIF.
A second problem can happen when the user dumps a cache entry
where a VIF, that was referenced at creation time, has been
removed.
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index 0b9d03c..d0a6092 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -1616,17 +1616,20 @@
int ct;
struct rtnexthop *nhp;
struct net *net = mfc_net(c);
- struct net_device *dev = net->ipv4.vif_table[c->mfc_parent].dev;
u8 *b = skb_tail_pointer(skb);
struct rtattr *mp_head;
- if (dev)
- RTA_PUT(skb, RTA_IIF, 4, &dev->ifindex);
+ /* If cache is unresolved, don't try to parse IIF and OIF */
+ if (c->mfc_parent > MAXVIFS)
+ return -ENOENT;
+
+ if (VIF_EXISTS(net, c->mfc_parent))
+ RTA_PUT(skb, RTA_IIF, 4, &net->ipv4.vif_table[c->mfc_parent].dev->ifindex);
mp_head = (struct rtattr *)skb_put(skb, RTA_LENGTH(0));
for (ct = c->mfc_un.res.minvif; ct < c->mfc_un.res.maxvif; ct++) {
- if (c->mfc_un.res.ttls[ct] < 255) {
+ if (VIF_EXISTS(net, ct) && c->mfc_un.res.ttls[ct] < 255) {
if (skb_tailroom(skb) < RTA_ALIGN(RTA_ALIGN(sizeof(*nhp)) + 4))
goto rtattr_failure;
nhp = (struct rtnexthop *)skb_put(skb, RTA_ALIGN(sizeof(*nhp)));