From: Stefano Brivio sbrivio@redhat.com
[ Upstream commit 40cb35d5dc04e7f89cbc7b1fc9b4b48d9f1e5343 ]
When we perform an inexact match on FIB nodes via fib6_locate_1(), longer prefixes will be preferred to shorter ones. However, it might happen that a node, with higher fn_bit value than some other, has no valid routing information.
In this case, we'll pick that node, but it will be discarded by the check on RTN_RTINFO in fib6_locate(), and we might miss nodes with valid routing information but with lower fn_bit value.
This is apparent when a routing exception is created for a default route: # ip -6 route list fc00:1::/64 dev veth_A-R1 proto kernel metric 256 pref medium fc00:2::/64 dev veth_A-R2 proto kernel metric 256 pref medium fc00:4::1 via fc00:2::2 dev veth_A-R2 metric 1024 pref medium fe80::/64 dev veth_A-R1 proto kernel metric 256 pref medium fe80::/64 dev veth_A-R2 proto kernel metric 256 pref medium default via fc00:1::2 dev veth_A-R1 metric 1024 pref medium # ip -6 route list cache fc00:4::1 via fc00:2::2 dev veth_A-R2 metric 1024 expires 593sec mtu 1500 pref medium fc00:3::1 via fc00:1::2 dev veth_A-R1 metric 1024 expires 593sec mtu 1500 pref medium # ip -6 route flush cache # node for default route is discarded Failed to send flush request: No such process # ip -6 route list cache fc00:3::1 via fc00:1::2 dev veth_A-R1 metric 1024 expires 586sec mtu 1500 pref medium
Check right away if the node has a RTN_RTINFO flag, before replacing the 'prev' pointer, that indicates the longest matching prefix found so far.
Fixes: 38fbeeeeccdb ("ipv6: prepare fib6_locate() for exception table") Signed-off-by: Stefano Brivio sbrivio@redhat.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- net/ipv6/ip6_fib.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c index bbb5ffb3397d..7091568b9f63 100644 --- a/net/ipv6/ip6_fib.c +++ b/net/ipv6/ip6_fib.c @@ -1529,7 +1529,8 @@ static struct fib6_node *fib6_locate_1(struct fib6_node *root, if (plen == fn->fn_bit) return fn;
- prev = fn; + if (fn->fn_flags & RTN_RTINFO) + prev = fn;
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