amt: fix wrong usage of pskb_may_pull()

It adds missing pskb_may_pull() in amt_update_handler() and
amt_multicast_data_handler().
And it fixes wrong parameter of pskb_may_pull() in
amt_advertisement_handler() and amt_membership_query_handler().

Reported-by: Jakub Kicinski <kuba@kernel.org>
Fixes: cbc21dc1cfe9 ("amt: add data plane of amt interface")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/amt.c b/drivers/net/amt.c
index ebee5f0..900948e 100644 (file)
--- a/drivers/net/amt.c
+++ b/drivers/net/amt.c
@@ -2220,8 +2220,7 @@ static bool amt_advertisement_handler(struct amt_dev *amt, struct sk_buff *skb)
        struct amt_header_advertisement *amta;
        int hdr_size;
 
-       hdr_size = sizeof(*amta) - sizeof(struct amt_header);
-
+       hdr_size = sizeof(*amta) + sizeof(struct udphdr);
        if (!pskb_may_pull(skb, hdr_size))
                return true;
 
@@ -2251,19 +2250,27 @@ static bool amt_multicast_data_handler(struct amt_dev *amt, struct sk_buff *skb)
        struct ethhdr *eth;
        struct iphdr *iph;
 
+       hdr_size = sizeof(*amtmd) + sizeof(struct udphdr);
+       if (!pskb_may_pull(skb, hdr_size))
+               return true;
+
        amtmd = (struct amt_header_mcast_data *)(udp_hdr(skb) + 1);
        if (amtmd->reserved || amtmd->version)
                return true;
 
-       hdr_size = sizeof(*amtmd) + sizeof(struct udphdr);
        if (iptunnel_pull_header(skb, hdr_size, htons(ETH_P_IP), false))
                return true;
+
        skb_reset_network_header(skb);
        skb_push(skb, sizeof(*eth));
        skb_reset_mac_header(skb);
        skb_pull(skb, sizeof(*eth));
        eth = eth_hdr(skb);
+
+       if (!pskb_may_pull(skb, sizeof(*iph)))
+               return true;
        iph = ip_hdr(skb);
+
        if (iph->version == 4) {
                if (!ipv4_is_multicast(iph->daddr))
                        return true;
@@ -2274,6 +2281,9 @@ static bool amt_multicast_data_handler(struct amt_dev *amt, struct sk_buff *skb)
        } else if (iph->version == 6) {
                struct ipv6hdr *ip6h;
 
+               if (!pskb_may_pull(skb, sizeof(*ip6h)))
+                       return true;
+
                ip6h = ipv6_hdr(skb);
                if (!ipv6_addr_is_multicast(&ip6h->daddr))
                        return true;
@@ -2306,8 +2316,7 @@ static bool amt_membership_query_handler(struct amt_dev *amt,
        struct iphdr *iph;
        int hdr_size, len;
 
-       hdr_size = sizeof(*amtmq) - sizeof(struct amt_header);
-
+       hdr_size = sizeof(*amtmq) + sizeof(struct udphdr);
        if (!pskb_may_pull(skb, hdr_size))
                return true;
 
@@ -2315,22 +2324,27 @@ static bool amt_membership_query_handler(struct amt_dev *amt,
        if (amtmq->reserved || amtmq->version)
                return true;
 
-       hdr_size = sizeof(*amtmq) + sizeof(struct udphdr) - sizeof(*eth);
+       hdr_size -= sizeof(*eth);
        if (iptunnel_pull_header(skb, hdr_size, htons(ETH_P_TEB), false))
                return true;
+
        oeth = eth_hdr(skb);
        skb_reset_mac_header(skb);
        skb_pull(skb, sizeof(*eth));
        skb_reset_network_header(skb);
        eth = eth_hdr(skb);
+       if (!pskb_may_pull(skb, sizeof(*iph)))
+               return true;
+
        iph = ip_hdr(skb);
        if (iph->version == 4) {
-               if (!ipv4_is_multicast(iph->daddr))
-                       return true;
                if (!pskb_may_pull(skb, sizeof(*iph) + AMT_IPHDR_OPTS +
                                   sizeof(*ihv3)))
                        return true;
 
+               if (!ipv4_is_multicast(iph->daddr))
+                       return true;
+
                ihv3 = skb_pull(skb, sizeof(*iph) + AMT_IPHDR_OPTS);
                skb_reset_transport_header(skb);
                skb_push(skb, sizeof(*iph) + AMT_IPHDR_OPTS);
@@ -2345,15 +2359,17 @@ static bool amt_membership_query_handler(struct amt_dev *amt,
                ip_eth_mc_map(iph->daddr, eth->h_dest);
 #if IS_ENABLED(CONFIG_IPV6)
        } else if (iph->version == 6) {
-               struct ipv6hdr *ip6h = ipv6_hdr(skb);
                struct mld2_query *mld2q;
+               struct ipv6hdr *ip6h;
 
-               if (!ipv6_addr_is_multicast(&ip6h->daddr))
-                       return true;
                if (!pskb_may_pull(skb, sizeof(*ip6h) + AMT_IP6HDR_OPTS +
                                   sizeof(*mld2q)))
                        return true;
 
+               ip6h = ipv6_hdr(skb);
+               if (!ipv6_addr_is_multicast(&ip6h->daddr))
+                       return true;
+
                mld2q = skb_pull(skb, sizeof(*ip6h) + AMT_IP6HDR_OPTS);
                skb_reset_transport_header(skb);
                skb_push(skb, sizeof(*ip6h) + AMT_IP6HDR_OPTS);
@@ -2389,23 +2405,23 @@ static bool amt_update_handler(struct amt_dev *amt, struct sk_buff *skb)
 {
        struct amt_header_membership_update *amtmu;
        struct amt_tunnel_list *tunnel;
-       struct udphdr *udph;
        struct ethhdr *eth;
        struct iphdr *iph;
-       int len;
+       int len, hdr_size;
 
        iph = ip_hdr(skb);
-       udph = udp_hdr(skb);
 
-       if (__iptunnel_pull_header(skb, sizeof(*udph), skb->protocol,
-                                  false, false))
+       hdr_size = sizeof(*amtmu) + sizeof(struct udphdr);
+       if (!pskb_may_pull(skb, hdr_size))
                return true;
 
-       amtmu = (struct amt_header_membership_update *)skb->data;
+       amtmu = (struct amt_header_membership_update *)(udp_hdr(skb) + 1);
        if (amtmu->reserved || amtmu->version)
                return true;
 
-       skb_pull(skb, sizeof(*amtmu));
+       if (iptunnel_pull_header(skb, hdr_size, skb->protocol, false))
+               return true;
+
        skb_reset_network_header(skb);
 
        list_for_each_entry_rcu(tunnel, &amt->tunnel_list, list) {
@@ -2426,6 +2442,9 @@ static bool amt_update_handler(struct amt_dev *amt, struct sk_buff *skb)
        return true;
 
 report:
+       if (!pskb_may_pull(skb, sizeof(*iph)))
+               return true;
+
        iph = ip_hdr(skb);
        if (iph->version == 4) {
                if (ip_mc_check_igmp(skb)) {