kernel/git/stable/linux.git/net/ipv6/ip6_fib.c, branch master

ipv6: fix fib6 walker UAF on seq stop

2026-09-10T15:39:06+00:00

ipv6_route_iter_active() treats a walker in FWS_U at the table root as already unlinked. fib6_del_route() can move a still-linked walker into that same state when the current leaf is the last route at the root, so ipv6_route_native_seq_stop() skips fib6_walker_unlink(). The seq private object can then be freed while it remains on net->ipv6.fib6_walkers. A later route deletion walks the dangling list and uses the freed walker. Use the list head as membership state and reinitialize it when unlinking. Keep the existing w->node check so a never-started iterator with a zeroed private object is not treated as linked. The same stop helper is used by /proc/net/ipv6_route and by the BPF ipv6_route iterator. The BPF show path only widens the race. Fixes: 8d2ca1d7b5c3 ("ipv6: avoid high order memory allocations for /proc/net/ipv6_route") Cc: stable@vger.kernel.org Reported-by: Vega Co-developed-by: Luxing Yin Signed-off-by: Luxing Yin Signed-off-by: Zihan Xi Reviewed-by: Ido Schimmel Link: https://patch.msgid.link/89699735763f6c297584d7c2ff106239cc1e8ce0.1788837093.git.zihanx@nebusec.ai Signed-off-by: Jakub Kicinski

ipv6: add inet6_rt_del_notify()

2026-08-13T10:30:27+00:00

Move the body of inet6_rt_notify() to __inet6_rt_notify() and give it the deletion reason. inet6_rt_notify() keeps its prototype, so the route addition path does not change. Add inet6_rt_del_notify() and call it from fib6_del_route(). RTA_DEL_REASON now reaches user space on RTM_DELROUTE for routes the kernel deleted on its own. Signed-off-by: Yuyang Huang Reviewed-by: Ido Schimmel Link: https://patch.msgid.link/20260808005642.26901-7-sigefriedhyy@gmail.com Signed-off-by: Paolo Abeni

ipv6: record the reason for kernel-initiated route deletions

2026-08-13T10:30:27+00:00

Record why the kernel deletes an IPv6 route on its own: - RT_DEL_REASON_EXPIRED for routes reaped by the FIB6 garbage collector after their RTF_EXPIRES lifetime ran out. - RT_DEL_REASON_RA_WITHDRAWN for default routes, prefix routes and RFC 4191 route information routes withdrawn by a zero-lifetime Router Advertisement. Deleting a default route because its metric changed is not a withdrawal, so it keeps RT_DEL_REASON_UNSPEC. Signed-off-by: Yuyang Huang Reviewed-by: Ido Schimmel Link: https://patch.msgid.link/20260808005642.26901-4-sigefriedhyy@gmail.com Signed-off-by: Paolo Abeni

ipv6: propagate the route deletion reason to fib6_del_route()

2026-08-13T10:30:27+00:00

Pass the deletion reason from ip6_del_rt_reason() down through __ip6_del_rt(), fib6_del() and into fib6_del_route(). All existing callers pass RT_DEL_REASON_UNSPEC. fib6_del_route() ignores the reason until the notification path learns to report it. Signed-off-by: Yuyang Huang Reviewed-by: Ido Schimmel Link: https://patch.msgid.link/20260808005642.26901-3-sigefriedhyy@gmail.com Signed-off-by: Paolo Abeni

ipv6: release fib6_null_entry on subtree failure

2026-07-29T23:49:39+00:00

When adding a source-specific route creates a new subtree, fib6_add() installs fib6_null_entry as the temporary leaf of the new subtree root and takes a fib6_info reference for that holder. If adding the first source leaf fails, the code frees the just allocated subtree root but leaves that hold behind. fib6_null_entry is a per-netns sentinel and is freed directly at netns teardown, so this does not keep the object alive. However, it leaves its visible refcount permanently elevated and can eventually saturate the refcount on repeated failures. Drop the null-entry reference before freeing the unlinked subtree root. Fixes: 5ea715289af6 ("ipv6: broadly use fib6_info_hold() helper") Signed-off-by: Shuangpeng Bai Reviewed-by: Ido Schimmel Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Link: https://patch.msgid.link/20260727185339.1545169-1-shuangpeng.kernel@gmail.com Signed-off-by: Jakub Kicinski

ipv6: fib6: fix NULL deref in fib6_walk_continue() on multi-batch dump

2026-06-30T01:28:41+00:00

inet6_dump_fib() saves its progress in cb->args[1] as a positional index within the current hash chain. Between batches, a concurrent fib6_new_table() can insert a new table at the chain head, shifting all existing entries. The saved index then lands on a different table, causing fib6_dump_table() to set w->root to the wrong table while w->node still points into the previous one. fib6_walk_continue() dereferences w->node->parent (NULL) and panics: BUG: kernel NULL pointer dereference, address: 0000000000000008 RIP: 0010:fib6_walk_continue+0x6e/0x170 Call Trace: fib6_dump_table.isra.0+0xc5/0x240 inet6_dump_fib+0xf6/0x420 rtnl_dumpit+0x30/0xa0 netlink_dump+0x15b/0x460 netlink_recvmsg+0x1d6/0x2a0 ____sys_recvmsg+0x17a/0x190 Fix by storing tb->tb6_id in cb->args[1] instead of a positional index. On resume, skip entries until the id matches; a concurrent head-insert can never match the saved id, so the walker always resumes on the correct table. Fixes: 1b43af5480c3 ("[IPV6]: Increase number of possible routing tables to 2^32") Signed-off-by: Pengfei Zhang Reviewed-by: Ido Schimmel Link: https://patch.msgid.link/20260625070517.965597-1-zhangfeionline@gmail.com Signed-off-by: Jakub Kicinski

net: Remove rtnl_held of struct fib_dump_filter.

2026-06-09T00:06:23+00:00

Commit 22e36ea9f5d7 ("inet: allow ip_valid_fib_dump_req() to be called with RTNL or RCU") introduced the rtnl_held field in struct fib_dump_filter to switch __dev_get_by_index() and dev_get_by_index_rcu() depending on the caller's context. This field served as an interim measure while we were incrementally converting all callers of ip_valid_fib_dump_req() to RCU. Now that all users (IPv4, IPv6, ipmr, ip6mr, and MPLS) have been converted to RCU, the field is no longer necessary. Let's remove it. Signed-off-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20260604224712.3209821-8-kuniyu@google.com Signed-off-by: Jakub Kicinski

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

2026-04-02T18:03:13+00:00

Cross-merge networking fixes after downstream PR (net-7.0-rc7). Conflicts: net/vmw_vsock/af_vsock.c b18c83388874 ("vsock: initialize child_ns_mode_locked in vsock_net_init()") 0de607dc4fd8 ("vsock: add G2H fallback for CIDs not owned by H2G transport") Adjacent changes: drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c ceee35e5674a ("bnxt_en: Refactor some basic ring setup and adjustment logic") 57cdfe0dc70b ("bnxt_en: Resize RSS contexts on channel count change") drivers/net/wireless/intel/iwlwifi/mld/mac80211.c 4d56037a02bd ("wifi: iwlwifi: mld: block EMLSR during TDLS connections") 687a95d204e7 ("wifi: iwlwifi: mld: correctly set wifi generation data") drivers/net/wireless/intel/iwlwifi/mld/scan.h b6045c899e37 ("wifi: iwlwifi: mld: Refactor scan command handling") ec66ec6a5a8f ("wifi: iwlwifi: mld: Fix MLO scan timing") drivers/net/wireless/intel/iwlwifi/mvm/fw.c 078df640ef05 ("wifi: iwlwifi: mld: add support for iwl_mcc_allowed_ap_type_cmd v 2") 323156c3541e ("wifi: iwlwifi: mvm: don't send a 6E related command when not supported") Signed-off-by: Jakub Kicinski

ipv6: fix data race in fib6_metric_set() using cmpxchg

2026-04-02T00:44:35+00:00

fib6_metric_set() may be called concurrently from softirq context without holding the FIB table lock. A typical path is: ndisc_router_discovery() spin_unlock_bh(&table->tb6_lock) <- lock released fib6_metric_set(rt, RTAX_HOPLIMIT, ...) <- lockless call When two CPUs process Router Advertisement packets for the same router simultaneously, they can both arrive at fib6_metric_set() with the same fib6_info pointer whose fib6_metrics still points to dst_default_metrics. if (f6i->fib6_metrics == &dst_default_metrics) { /* both CPUs: true */ struct dst_metrics *p = kzalloc_obj(*p, GFP_ATOMIC); refcount_set(&p->refcnt, 1); f6i->fib6_metrics = p; /* CPU1 overwrites CPU0's p -> p0 leaked */ } The dst_metrics allocated by the losing CPU has refcnt=1 but no pointer to it anywhere in memory, producing a kmemleak report: unreferenced object 0xff1100025aca1400 (size 96): comm "softirq", pid 0, jiffies 4299271239 backtrace: kmalloc_trace+0x28a/0x380 fib6_metric_set+0xcd/0x180 ndisc_router_discovery+0x12dc/0x24b0 icmpv6_rcv+0xc16/0x1360 Fix this by: - Set val for p->metrics before published via cmpxchg() so the metrics value is ready before the pointer becomes visible to other CPUs. - Replace the plain pointer store with cmpxchg() and free the allocation safely when competition failed. - Add READ_ONCE()/WRITE_ONCE() for metrics[] setting in the non-default metrics path to prevent compiler-based data races. Fixes: d4ead6b34b67 ("net/ipv6: move metrics from dst to rt6_info") Reported-by: Fei Liu Reviewed-by: Jiayuan Chen Signed-off-by: Hangbin Liu Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20260331-b4-fib6_metric_set-kmemleak-v3-1-88d27f4d8825@gmail.com Signed-off-by: Jakub Kicinski

ipv6: remove ipv6_stub infrastructure completely

2026-03-29T18:21:24+00:00

As IPv6 is built-in only and there are no more users of ipv6_stub, the ipv6_stub is now entirely obsolete. Remove all the code related to the definition, initialization and usage. Signed-off-by: Fernando Fernandez Mancera Tested-by: Ricardo B. Marlière Link: https://patch.msgid.link/20260325120928.15848-11-fmancera@suse.de Signed-off-by: Jakub Kicinski