netfilter: nf_queue: do not allow packet truncation below transport h…

…eader offset [ Upstream commit 99a63d3 ] Domingo Dirutigliano and Nicola Guerrera report kernel panic when sending nf_queue verdict with 1-byte nfta_payload attribute. The IP/IPv6 stack pulls the IP(v6) header from the packet after the input hook. If user truncates the packet below the header size, this skb_pull() will result in a malformed skb (skb->len < 0). Fixes: 7af4cc3 ("[NETFILTER]: Add "nfnetlink_queue" netfilter queue handler over nfnetlink") Reported-by: Domingo Dirutigliano <[email protected]> Signed-off-by: Florian Westphal <[email protected]> Reviewed-by: Pablo Neira Ayuso <[email protected]> Signed-off-by: Sasha Levin <[email protected]>
ammarfaizi2 · Aug 1, 2022 · d4cc8d6 · d4cc8d6
1 parent 7fe415d
commit d4cc8d6
Showing 1 changed file with 6 additions and 1 deletion.
diff --git a/net/netfilter/nfnetlink_queue.c b/net/netfilter/nfnetlink_queue.c
@@ -838,11 +838,16 @@ nfqnl_enqueue_packet(struct nf_queue_entry *entry, unsigned int queuenum)
 }
 
 static int
-nfqnl_mangle(void *data, int data_len, struct nf_queue_entry *e, int diff)
+nfqnl_mangle(void *data, unsigned int data_len, struct nf_queue_entry *e, int diff)
 {
 	struct sk_buff *nskb;
 
 	if (diff < 0) {
+		unsigned int min_len = skb_transport_offset(e->skb);
+
+		if (data_len < min_len)
+			return -EINVAL;
+
 		if (pskb_trim(e->skb, data_len))
 			return -ENOMEM;
 	} else if (diff > 0) {