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ipvs: clear IPv4 options after rebasing tunnel ICMP errors

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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: f2edb9f770 ("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 <kylebot@openai.com>
Co-developed-by: David Lee <david.lee@trailofbits.com>
Signed-off-by: David Lee <david.lee@trailofbits.com>
Acked-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Kyle Zeng
2026-08-04 06:10:55 +00:00
committed by Pablo Neira Ayuso
parent 33d1469b01
commit e0ba936287
1 changed files with 1 additions and 0 deletions
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1
net/netfilter/ipvs/ip_vs_core.c
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@@ -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;