From: Fernando Fernandez Mancera Date: Sat, 15 Nov 2025 10:59:38 +0100 Subject: ipv6: clear RA flags when adding a static route Origin: https://git.kernel.org/linus/f72514b3c5698e4b900b25345e09f9ed33123de6 Bug-Debian: https://bugs.debian.org/1117959 When an IPv6 Router Advertisement (RA) is received for a prefix, the kernel creates the corresponding on-link route with flags RTF_ADDRCONF and RTF_PREFIX_RT configured and RTF_EXPIRES if lifetime is set. If later a user configures a static IPv6 address on the same prefix the kernel clears the RTF_EXPIRES flag but it doesn't clear the RTF_ADDRCONF and RTF_PREFIX_RT. When the next RA for that prefix is received, the kernel sees the route as RA-learned and wrongly configures back the lifetime. This is problematic because if the route expires, the static address won't have the corresponding on-link route. This fix clears the RTF_ADDRCONF and RTF_PREFIX_RT flags preventing that the lifetime is configured when the next RA arrives. If the static address is deleted, the route becomes RA-learned again. Fixes: 14ef37b6d00e ("ipv6: fix route lookup in addrconf_prefix_rcv()") Reported-by: Garri Djavadyan Closes: https://lore.kernel.org/netdev/ba807d39aca5b4dcf395cc11dca61a130a52cfd3.camel@gmail.com/ Signed-off-by: Fernando Fernandez Mancera Reviewed-by: David Ahern Link: https://patch.msgid.link/20251115095939.6967-1-fmancera@suse.de Signed-off-by: Jakub Kicinski --- net/ipv6/ip6_fib.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c index 02c16909f618..2111af022d94 100644 --- a/net/ipv6/ip6_fib.c +++ b/net/ipv6/ip6_fib.c @@ -1138,6 +1138,10 @@ static int fib6_add_rt2node(struct fib6_node *fn, struct fib6_info *rt, fib6_set_expires(iter, rt->expires); fib6_add_gc_list(iter); } + if (!(rt->fib6_flags & (RTF_ADDRCONF | RTF_PREFIX_RT))) { + iter->fib6_flags &= ~RTF_ADDRCONF; + iter->fib6_flags &= ~RTF_PREFIX_RT; + } if (rt->fib6_pmtu) fib6_metric_set(iter, RTAX_MTU, -- 2.51.0