ipv6: fix possible infinite loop in fib6_select_path()

Summary

In the Linux kernel, the following vulnerability has been resolved: ipv6: fix possible infinite loop in fib6_select_path() Found while auditing the same pattern Sashiko reported in rt6_fill_node() [1]. Apply the same fix as commit f8d8ce1b515a ("ipv6: fix possible infinite loop in fib6_info_uses_dev()"). Writers holding tb6_lock can list_del_rcu(&first->fib6_siblings) without waiting for RCU readers; first->fib6_siblings.next then still points into the old ring and this softirq-side walker never reaches &first->fib6_siblings as its terminator. fib6_purge_rt() always WRITE_ONCE()s first->fib6_nsiblings to 0 before list_del_rcu(), so an inside-loop check is a reliable detach signal. [1] https://sashiko.dev/#/patchset/20260526020227.4857-1-jiayuan.chen%40linux.dev

Timeline

1. Jul 19, 2026, 2:55 PM UTCCVE published
2. Oct 16, 2026, 3:34 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: yes · Technical impact: partial

3. Oct 19, 2026, 8:17 PM UTCRecord last updated

Affected versions

• Linux Linux

  From d0ec61c9f3583b76aebdbb271f5c0d3fcccd48b2 · fixed in 3948a7d92f7678e89e1776bb2d169afcad63b1ae; From 52da02521ede55fb86546c3fffd9377b3261b91f · fixed in c87cd3cb309634bc8f50a54e2079424f219ac21f; From 34a949e7a0869dfa31a40416d2a56973fae1807b · fixed in 0f7b73c3452635de83b8711b31abdda8e49aad7b; From d9ccb18f83ea2bb654289b6ecf014fd267cc988b · fixed in ab9a10969a907b472a0196d999c08ff7144172e3; From d9ccb18f83ea2bb654289b6ecf014fd267cc988b · fixed in 9b9d5bd6e3d4c9cecab5407604b690684b2532d2; From d9ccb18f83ea2bb654289b6ecf014fd267cc988b · fixed in 9c7da87c2dc860bb17ca1ece942495d28b1ce3b9; From 6.1.128 · fixed in 6.1.176; From 6.6.75 · fixed in 6.6.143; From 6.12.2 · fixed in 6.12.93; From 6.11.11 · fixed in 6.12

• Linux Linux

  6.13

• KernelLinux

  fixed in 6.1.176; From 6.2.0 · fixed in 6.6.143; From 6.7.0 · fixed in 6.12.93; From 6.13.0 · fixed in 6.18.35; fixed in 7.0.12

References 6