From: Kyle Zeng ip_vs_in_icmp() rebases an skb from the outer ICMP packet to the quoted original request before passing it to icmp_send(). However, IPCB(skb)->opt still describes the outer IPv4 header. A timestamp option in the outer header can therefore leave an offset that points into the quoted transport header after the rebase. __ip_options_echo() treats a byte at that stale location as the option length and copies it into the fixed-size option storage on the __icmp_send() stack, causing a stack out-of-bounds write. Clear the stale option metadata after resetting the network header. Keep the remaining control block fields, including the ingress interface used by the ICMP response path. Fixes: f2edb9f7706d ("ipvs: implement passive PMTUD for IPIP packets") Cc: stable@vger.kernel.org Assisted-by: Codex:gpt-5.6-sol Codex:gpt-5.5-cyber Signed-off-by: Kyle Zeng Co-developed-by: David Lee Signed-off-by: David Lee Acked-by: Julian Anastasov Signed-off-by: Pablo Neira Ayuso --- net/netfilter/ipvs/ip_vs_core.c | 1 + 1 file changed, 1 insertion(+) diff --git a/net/netfilter/ipvs/ip_vs_core.c b/net/netfilter/ipvs/ip_vs_core.c index 95af77b68851..a46e7acdd8e1 100644 --- a/net/netfilter/ipvs/ip_vs_core.c +++ b/net/netfilter/ipvs/ip_vs_core.c @@ -1950,6 +1950,7 @@ ip_vs_in_icmp(struct netns_ipvs *ipvs, struct sk_buff *skb, int *related, if (pskb_pull(skb, offset2) == NULL) goto ignore_tunnel; skb_reset_network_header(skb); + memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt)); /* Ensure the IP header is present in headroom */ if (!pskb_may_pull(skb, hlen_orig)) goto ignore_tunnel; -- 2.47.3