netfilter: ip6tables: mark malformed IPv6 extension headers for hotdrop

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The ah, hbh and rt matches check that the fixed extension header is
present, then use the header length field to derive the advertised
extension header length for matching.

For the ah match, add the missing advertised-length check. For hbh
and rt, update the existing advertised-length checks. In all three
cases, set hotdrop to true before returning false when the advertised
extension header length exceeds the available skb data.

Returning false treats the packet as a rule mismatch. Set hotdrop to
true and drop malformed packets so they cannot bypass rules intended
to drop packets with these IPv6 extension headers.

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Zhixing Chen <running910@gmail.com>
Signed-off-by: Florian Westphal <fw@strlen.de>

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Zhixing Chen 2026-07-01 18:09:30 +08:00 • committed by Florian Westphal

parent 278296b69f

commit 43ccc20b5a

3 changed files with 8 additions and 1 deletions

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5

net/ipv6/netfilter/ip6t_ah.c

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1

net/ipv6/netfilter/ip6t_hbh.c

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3

net/ipv6/netfilter/ip6t_rt.c

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