kernel.git/net/ipv6/route.c, branch linux-6.15.y

ipv6: annotate data-races around rt->fib6_nsiblings

2025-08-15T10:16:37Z

[ Upstream commit 31d7d67ba1274f42494256d52e86da80ed09f3cb ] rt->fib6_nsiblings can be read locklessly, add corresponding READ_ONCE() and WRITE_ONCE() annotations. Fixes: 66f5d6ce53e6 ("ipv6: replace rwlock with rcu and spinlock in fib6_table") Signed-off-by: Eric Dumazet Link: https://patch.msgid.link/20250725140725.3626540-5-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

ipv6: fix possible infinite loop in fib6_info_uses_dev()

2025-08-15T10:16:37Z

[ Upstream commit f8d8ce1b515a0a6af72b30502670a406cfb75073 ] fib6_info_uses_dev() seems to rely on RCU without an explicit protection. Like the prior fix in rt6_nlmsg_size(), we need to make sure fib6_del_route() or fib6_add_rt2node() have not removed the anchor from the list, or we risk an infinite loop. Fixes: d9ccb18f83ea ("ipv6: Fix soft lockups in fib6_select_path under high next hop churn") Signed-off-by: Eric Dumazet Link: https://patch.msgid.link/20250725140725.3626540-4-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

ipv6: prevent infinite loop in rt6_nlmsg_size()

2025-08-15T10:16:37Z

[ Upstream commit 54e6fe9dd3b0e7c481c2228782c9494d653546da ] While testing prior patch, I was able to trigger an infinite loop in rt6_nlmsg_size() in the following place: list_for_each_entry_rcu(sibling, &f6i->fib6_siblings, fib6_siblings) { rt6_nh_nlmsg_size(sibling->fib6_nh, &nexthop_len); } This is because fib6_del_route() and fib6_add_rt2node() uses list_del_rcu(), which can confuse rcu readers, because they might no longer see the head of the list. Restart the loop if f6i->fib6_nsiblings is zero. Fixes: d9ccb18f83ea ("ipv6: Fix soft lockups in fib6_select_path under high next hop churn") Signed-off-by: Eric Dumazet Link: https://patch.msgid.link/20250725140725.3626540-3-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

ipv6: add exception routes to GC list in rt6_insert_exception

2025-04-11T03:09:05Z

Commit 5eb902b8e719 ("net/ipv6: Remove expired routes with a separated list of routes.") introduced a separated list for managing route expiration via the GC timer. However, it missed adding exception routes (created by ip6_rt_update_pmtu() and rt6_do_redirect()) to this GC list. As a result, these exceptions were never considered for expiration and removal, leading to stale entries persisting in the routing table. This patch fixes the issue by calling fib6_add_gc_list() in rt6_insert_exception(), ensuring that exception routes are properly tracked and garbage collected when expired. Fixes: 5eb902b8e719 ("net/ipv6: Remove expired routes with a separated list of routes.") Reported-by: Jianlin Shi Signed-off-by: Xin Long Reviewed-by: David Ahern Link: https://patch.msgid.link/837e7506ffb63f47faa2b05d9b85481aad28e1a4.1744134377.git.lucien.xin@gmail.com Signed-off-by: Jakub Kicinski

ipv6: Align behavior across nexthops during path selection

2025-04-10T01:00:06Z

A nexthop is only chosen when the calculated multipath hash falls in the nexthop's hash region (i.e., the hash is smaller than the nexthop's hash threshold) and when the nexthop is assigned a non-negative score by rt6_score_route(). Commit 4d0ab3a6885e ("ipv6: Start path selection from the first nexthop") introduced an unintentional difference between the first nexthop and the rest when the score is negative. When the first nexthop matches, but has a negative score, the code will currently evaluate subsequent nexthops until one is found with a non-negative score. On the other hand, when a different nexthop matches, but has a negative score, the code will fallback to the nexthop with which the selection started ('match'). Align the behavior across all nexthops and fallback to 'match' when the first nexthop matches, but has a negative score. Fixes: 3d709f69a3e7 ("ipv6: Use hash-threshold instead of modulo-N") Fixes: 4d0ab3a6885e ("ipv6: Start path selection from the first nexthop") Reported-by: Willem de Bruijn Closes: https://lore.kernel.org/netdev/67efef607bc41_1ddca82948c@willemb.c.googlers.com.notmuch/ Signed-off-by: Ido Schimmel Reviewed-by: Willem de Bruijn Reviewed-by: David Ahern Link: https://patch.msgid.link/20250408084316.243559-1-idosch@nvidia.com Signed-off-by: Jakub Kicinski

ipv6: Do not consider link down nexthops in path selection

2025-04-04T14:30:07Z

Nexthops whose link is down are not supposed to be considered during path selection when the "ignore_routes_with_linkdown" sysctl is set. This is done by assigning them a negative region boundary. However, when comparing the computed hash (unsigned) with the region boundary (signed), the negative region boundary is treated as unsigned, resulting in incorrect nexthop selection. Fix by treating the computed hash as signed. Note that the computed hash is always in range of [0, 2^31 - 1]. Fixes: 3d709f69a3e7 ("ipv6: Use hash-threshold instead of modulo-N") Signed-off-by: Ido Schimmel Reviewed-by: Willem de Bruijn Link: https://patch.msgid.link/20250402114224.293392-3-idosch@nvidia.com Signed-off-by: Jakub Kicinski

ipv6: Start path selection from the first nexthop

2025-04-04T14:30:07Z

Cited commit transitioned IPv6 path selection to use hash-threshold instead of modulo-N. With hash-threshold, each nexthop is assigned a region boundary in the multipath hash function's output space and a nexthop is chosen if the calculated hash is smaller than the nexthop's region boundary. Hash-threshold does not work correctly if path selection does not start with the first nexthop. For example, if fib6_select_path() is always passed the last nexthop in the group, then it will always be chosen because its region boundary covers the entire hash function's output space. Fix this by starting the selection process from the first nexthop and do not consider nexthops for which rt6_score_route() provided a negative score. Fixes: 3d709f69a3e7 ("ipv6: Use hash-threshold instead of modulo-N") Reported-by: Stanislav Fomichev Closes: https://lore.kernel.org/netdev/Z9RIyKZDNoka53EO@mini-arch/ Signed-off-by: Ido Schimmel Link: https://patch.msgid.link/20250402114224.293392-2-idosch@nvidia.com Signed-off-by: Jakub Kicinski

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

2025-03-20T20:38:01Z

Cross-merge networking fixes after downstream PR (net-6.14-rc8). Conflict: tools/testing/selftests/net/Makefile 03544faad761 ("selftest: net: add proc_net_pktgen") 3ed61b8938c6 ("selftests: net: test for lwtunnel dst ref loops") tools/testing/selftests/net/config: 85cb3711acb8 ("selftests: net: Add test cases for link and peer netns") 3ed61b8938c6 ("selftests: net: test for lwtunnel dst ref loops") Adjacent commits: tools/testing/selftests/net/Makefile c935af429ec2 ("selftests: net: add support for testing SO_RCVMARK and SO_RCVPRIORITY") 355d940f4d5a ("Revert "selftests: Add IPv6 link-local address generation tests for GRE devices."") Signed-off-by: Paolo Abeni

ipv6: Set errno after ip_fib_metrics_init() in ip6_route_info_create().

2025-03-18T11:58:08Z

While creating a new IPv6, we could get a weird -ENOMEM when RTA_NH_ID is set and either of the conditions below is true: 1) CONFIG_IPV6_SUBTREES is enabled and rtm_src_len is specified 2) nexthop_get() fails e.g.) # strace ip -6 route add fe80::dead:beef:dead:beef nhid 1 from :: recvmsg(3, {msg_iov=[{iov_base=[...[ {error=-ENOMEM, msg=[... [...]]}, [{nla_len=49, nla_type=NLMSGERR_ATTR_MSG}, "Nexthops can not be used with so"...] ]], iov_len=32768}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, 0) = 148 Let's set err explicitly after ip_fib_metrics_init() in ip6_route_info_create(). Fixes: f88d8ea67fbd ("ipv6: Plumb support for nexthop object in a fib6_info") Signed-off-by: Kuniyuki Iwashima Reviewed-by: David Ahern Link: https://patch.msgid.link/20250312013854.61125-1-kuniyu@amazon.com Signed-off-by: Paolo Abeni

ipv6: Fix memleak of nhc_pcpu_rth_output in fib_check_nh_v6_gw().

2025-03-18T11:55:11Z

fib_check_nh_v6_gw() expects that fib6_nh_init() cleans up everything when it fails. Commit 7dd73168e273 ("ipv6: Always allocate pcpu memory in a fib6_nh") moved fib_nh_common_init() before alloc_percpu_gfp() within fib6_nh_init() but forgot to add cleanup for fib6_nh->nh_common.nhc_pcpu_rth_output in case it fails to allocate fib6_nh->rt6i_pcpu, resulting in memleak. Let's call fib_nh_common_release() and clear nhc_pcpu_rth_output in the error path. Note that we can remove the fib6_nh_release() call in nh_create_ipv6() later in net-next.git. Fixes: 7dd73168e273 ("ipv6: Always allocate pcpu memory in a fib6_nh") Signed-off-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250312010333.56001-1-kuniyu@amazon.com Signed-off-by: Paolo Abeni