kernel/linux.git/net/ipv6/ndisc.c, branch v6.6.148

ipv6: ndisc: fix NULL deref in accept_untracked_na()

2026-08-03T09:15:32+00:00

commit d186e942365acece7c56d39da05dd63bf95b280a upstream. accept_untracked_na() re-fetches the inet6_dev with __in6_dev_get(dev) and dereferences idev->cnf.accept_untracked_na without a NULL check, even though its only caller ndisc_recv_na() already fetched and NULL-checked idev for the same device. Both reads of dev->ip6_ptr run in the same RCU read-side critical section, but a concurrent addrconf_ifdown() can clear dev->ip6_ptr between them: lowering the MTU below IPV6_MIN_MTU calls addrconf_ifdown() without the synchronize_net() that orders the unregister path, so the re-fetch returns NULL and oopses: BUG: KASAN: null-ptr-deref in ndisc_recv_na (net/ipv6/ndisc.c:974) Read of size 4 at addr 0000000000000364 Call Trace: ndisc_recv_na (net/ipv6/ndisc.c:974) icmpv6_rcv (net/ipv6/icmp.c:1193) ip6_protocol_deliver_rcu (net/ipv6/ip6_input.c:479) ip6_input_finish (net/ipv6/ip6_input.c:534) ip6_input (net/ipv6/ip6_input.c:545) ip6_mc_input (net/ipv6/ip6_input.c:635) ipv6_rcv (net/ipv6/ip6_input.c:351) It is reachable by an unprivileged user via a network namespace. Pass the caller's already validated idev instead of re-fetching it; the idev stays alive for the whole RCU critical section, so it is safe even after dev->ip6_ptr has been cleared. Fixes: aaa5f515b16b ("net: ipv6: new accept_untracked_na option to accept na only if in-network") Reported-by: Xiang Mei Signed-off-by: Weiming Shi Reviewed-by: Jiayuan Chen Link: https://patch.msgid.link/20260617065512.2529757-2-bestswngs@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Alexander Martyniuk Signed-off-by: Sasha Levin

ipv6/addrconf: annotate data-races around devconf fields (II)

2026-06-19T11:39:39+00:00

[ Upstream commit 2f0ff05a44302c91af54a5f9efe1b65b7681540e ] Final (?) round of this series. Annotate lockless reads on following devconf fields, because they be changed concurrently from /proc/net/ipv6/conf. - accept_dad - optimistic_dad - use_optimistic - use_oif_addrs_only - ra_honor_pio_life - keep_addr_on_down - ndisc_notify - ndisc_evict_nocarrier - suppress_frag_ndisc - addr_gen_mode - seg6_enabled - ioam6_enabled - ioam6_id - ioam6_id_wide - drop_unicast_in_l2_multicast - mldv[12]_unsolicited_report_interval - force_mld_version - force_tllao - accept_untracked_na - drop_unsolicited_na - accept_source_route Signed-off-by: Eric Dumazet Reviewed-by: Jiri Pirko Signed-off-by: David S. Miller Stable-dep-of: d4ea0dfd7501 ("ipv6: ioam: add NULL check for idev in ipv6_hop_ioam()") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

net: ipv6: ndisc: fix ndisc_ra_useropt to initialize nduseropt_padX fields to zero to prevent an info-leak

2026-04-11T12:19:19+00:00

[ Upstream commit ae05340ccaa9d347fe85415609e075545bec589f ] When processing Router Advertisements with user options the kernel builds an RTM_NEWNDUSEROPT netlink message. The nduseroptmsg struct has three padding fields that are never zeroed and can leak kernel data The fix is simple, just zeroes the padding fields. Fixes: 31910575a9de ("[IPv6]: Export userland ND options through netlink (RDNSS support)") Signed-off-by: Yochai Eisenrich Reviewed-by: Simon Horman Link: https://patch.msgid.link/20260324224925.2437775-1-echelonh@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

ipv6: annotate data-race in ndisc_router_discovery()

2026-01-30T09:27:36+00:00

[ Upstream commit 9a063f96d87efc3a6cc667f8de096a3d38d74bb5 ] syzbot found that ndisc_router_discovery() could read and write in6_dev->ra_mtu without holding a lock [1] This looks fine, IFLA_INET6_RA_MTU is best effort. Add READ_ONCE()/WRITE_ONCE() to document the race. Note that we might also reject illegal MTU values (mtu < IPV6_MIN_MTU || mtu > skb->dev->mtu) in a future patch. [1] BUG: KCSAN: data-race in ndisc_router_discovery / ndisc_router_discovery read to 0xffff888119809c20 of 4 bytes by task 25817 on cpu 1: ndisc_router_discovery+0x151d/0x1c90 net/ipv6/ndisc.c:1558 ndisc_rcv+0x2ad/0x3d0 net/ipv6/ndisc.c:1841 icmpv6_rcv+0xe5a/0x12f0 net/ipv6/icmp.c:989 ip6_protocol_deliver_rcu+0xb2a/0x10d0 net/ipv6/ip6_input.c:438 ip6_input_finish+0xf0/0x1d0 net/ipv6/ip6_input.c:489 NF_HOOK include/linux/netfilter.h:318 [inline] ip6_input+0x5e/0x140 net/ipv6/ip6_input.c:500 ip6_mc_input+0x27c/0x470 net/ipv6/ip6_input.c:590 dst_input include/net/dst.h:474 [inline] ip6_rcv_finish+0x336/0x340 net/ipv6/ip6_input.c:79 ... write to 0xffff888119809c20 of 4 bytes by task 25816 on cpu 0: ndisc_router_discovery+0x155a/0x1c90 net/ipv6/ndisc.c:1559 ndisc_rcv+0x2ad/0x3d0 net/ipv6/ndisc.c:1841 icmpv6_rcv+0xe5a/0x12f0 net/ipv6/icmp.c:989 ip6_protocol_deliver_rcu+0xb2a/0x10d0 net/ipv6/ip6_input.c:438 ip6_input_finish+0xf0/0x1d0 net/ipv6/ip6_input.c:489 NF_HOOK include/linux/netfilter.h:318 [inline] ip6_input+0x5e/0x140 net/ipv6/ip6_input.c:500 ip6_mc_input+0x27c/0x470 net/ipv6/ip6_input.c:590 dst_input include/net/dst.h:474 [inline] ip6_rcv_finish+0x336/0x340 net/ipv6/ip6_input.c:79 ... value changed: 0x00000000 -> 0xe5400659 Fixes: 49b99da2c9ce ("ipv6: add IFLA_INET6_RA_MTU to expose mtu value") Reported-by: syzbot Signed-off-by: Eric Dumazet Cc: Rocco Yue Link: https://patch.msgid.link/20260118152941.2563857-1-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net/ipv6: Remove expired routes with a separated list of routes.

2026-01-11T14:21:26+00:00

[ Upstream commit 5eb902b8e7193cdcb33242af0a56502e6b5206e9 ] FIB6 GC walks trees of fib6_tables to remove expired routes. Walking a tree can be expensive if the number of routes in a table is big, even if most of them are permanent. Checking routes in a separated list of routes having expiration will avoid this potential issue. Reviewed-by: David Ahern Signed-off-by: Kui-Feng Lee Signed-off-by: David S. Miller Stable-dep-of: f72514b3c569 ("ipv6: clear RA flags when adding a static route") Signed-off-by: Sasha Levin

ndisc: extend RCU protection in ndisc_send_skb()

2025-02-21T12:57:24+00:00

[ Upstream commit ed6ae1f325d3c43966ec1b62ac1459e2b8e45640 ] ndisc_send_skb() can be called without RTNL or RCU held. Acquire rcu_read_lock() earlier, so that we can use dev_net_rcu() and avoid a potential UAF. Fixes: 1762f7e88eb3 ("[NETNS][IPV6] ndisc - make socket control per namespace") Signed-off-by: Eric Dumazet Reviewed-by: David Ahern Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250207135841.1948589-8-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

ndisc: use RCU protection in ndisc_alloc_skb()

2025-02-21T12:57:23+00:00

[ Upstream commit 628e6d18930bbd21f2d4562228afe27694f66da9 ] ndisc_alloc_skb() can be called without RTNL or RCU being held. Add RCU protection to avoid possible UAF. Fixes: de09334b9326 ("ndisc: Introduce ndisc_alloc_skb() helper.") Signed-off-by: Eric Dumazet Reviewed-by: David Ahern Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250207135841.1948589-3-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

ndisc: ndisc_send_redirect() must use dev_get_by_index_rcu()

2025-02-21T12:57:07+00:00

[ Upstream commit 48145a57d4bbe3496e8e4880b23ea6b511e6e519 ] ndisc_send_redirect() is called under RCU protection, not RTNL. It must use dev_get_by_index_rcu() instead of __dev_get_by_index() Fixes: 2f17becfbea5 ("vrf: check the original netdevice for generating redirect") Signed-off-by: Eric Dumazet Cc: Stephen Suryaputra Reviewed-by: David Ahern Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250207135841.1948589-2-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

inetpeer: do not get a refcount in inet_getpeer()

2025-02-08T08:51:53+00:00

[ Upstream commit a853c609504e2d1d83e71285e3622fda1f1451d8 ] All inet_getpeer() callers except ip4_frag_init() don't need to acquire a permanent refcount on the inetpeer. They can switch to full RCU protection. Move the refcount_inc_not_zero() into ip4_frag_init(), so that all the other callers no longer have to perform a pair of expensive atomic operations on a possibly contended cache line. inet_putpeer() no longer needs to be exported. After this patch, my DUT can receive 8,400,000 UDP packets per second targeting closed ports, using 50% less cpu cycles than before. Also change two calls to l3mdev_master_ifindex() by l3mdev_master_ifindex_rcu() (Ido ideas) Fixes: 8c2bd38b95f7 ("icmp: change the order of rate limits") Signed-off-by: Eric Dumazet Link: https://patch.msgid.link/20241215175629.1248773-5-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

inetpeer: remove create argument of inet_getpeer_v[46]()

2025-02-08T08:51:53+00:00

[ Upstream commit 661cd8fc8e9039819ca0c22e0add52b632240a9e ] All callers of inet_getpeer_v4() and inet_getpeer_v6() want to create an inetpeer. Signed-off-by: Eric Dumazet Link: https://patch.msgid.link/20241215175629.1248773-2-edumazet@google.com Signed-off-by: Jakub Kicinski Stable-dep-of: a853c609504e ("inetpeer: do not get a refcount in inet_getpeer()") Signed-off-by: Sasha Levin