CVE-2026-98485netfilter: ip6t_rt: fix zero-address non-strict match out-of-bounds read

Official description

In the Linux kernel, the following vulnerability has been resolved: netfilter: ip6t_rt: fix zero-address non-strict match out-of-bounds read rt_mt6_check() permits rules to be configured with rtinfo->addrnr == 0 even when address matching (IP6T_RT_FST_MASK) is requested. In the IP6T_RT_FST_NSTRICT path, rt_mt6() evaluates packet routing addresses against rtinfo->addrs[i] and terminates backwards at the bottom of the loop: if (ipv6_addr_equal(ap, &rtinfo->addrs[i])) { i++; } if (i == rtinfo->addrnr) break; When addrnr is 0, if the first packet address matches rtinfo->addrs[0], i is incremented to 1. Because i is now strictly greater than addrnr (0), the loop termination condition (i == rtinfo->addrnr) is bypassed and will never be satisfied. If a crafted IPv6 packet contains matching routing addresses, i will advance past IP6T_RT_HOPS (16). The subsequent call to ipv6_addr_equal() reads beyond struct ip6t_rt, triggering UBSAN/KASAN out-of-bounds warnings or kernel panics. Fix this by: 1. Rejecting rules in rt_mt6_check() where IP6T_RT_FST_MASK is set but rtinfo->addrnr is zero. 2. In rt_mt6(), moving the termination condition (i < rtinfo->addrnr) into the for-loop header condition and removing the backwards break at the end of the loop body.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/959d1829d1ce8b91b435b24a923b51bcc8897090
• https://git.kernel.org/stable/c/fe336bab13834394320997de8b16ca4a913b4f13
• https://git.kernel.org/stable/c/5a54f8b7f7fe207a5c14713015a5820588faf1ad
• https://git.kernel.org/stable/c/b89249819a7d6698bed152feafd3bc6c08489d15
• https://git.kernel.org/stable/c/dd55c0ea87bf70e4e4b3b683acd29ef981335b26
• https://git.kernel.org/stable/c/191239b0939692e92459d8d32cad14247fa93f89
• https://git.kernel.org/stable/c/d9cf4ac6f326330e1fe4d95671d36a6ff3593f64
• https://git.kernel.org/stable/c/82313c169eddc02b1bf5ba6b427803e272d3ec42