kernel/linux.git/net/ipv4/icmp.c, branch v6.6.141

net: Fix icmp host relookup triggering ip_rt_bug

2026-05-17T15:13:35+00:00

[ Upstream commit c44daa7e3c73229f7ac74985acb8c7fb909c4e0a ] arp link failure may trigger ip_rt_bug while xfrm enabled, call trace is: WARNING: CPU: 0 PID: 0 at net/ipv4/route.c:1241 ip_rt_bug+0x14/0x20 Modules linked in: CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.12.0-rc6-00077-g2e1b3cc9d7f7 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 RIP: 0010:ip_rt_bug+0x14/0x20 Call Trace: ip_send_skb+0x14/0x40 __icmp_send+0x42d/0x6a0 ipv4_link_failure+0xe2/0x1d0 arp_error_report+0x3c/0x50 neigh_invalidate+0x8d/0x100 neigh_timer_handler+0x2e1/0x330 call_timer_fn+0x21/0x120 __run_timer_base.part.0+0x1c9/0x270 run_timer_softirq+0x4c/0x80 handle_softirqs+0xac/0x280 irq_exit_rcu+0x62/0x80 sysvec_apic_timer_interrupt+0x77/0x90 The script below reproduces this scenario: ip xfrm policy add src 0.0.0.0/0 dst 0.0.0.0/0 \ dir out priority 0 ptype main flag localok icmp ip l a veth1 type veth ip a a 192.168.141.111/24 dev veth0 ip l s veth0 up ping 192.168.141.155 -c 1 icmp_route_lookup() create input routes for locally generated packets while xfrm relookup ICMP traffic.Then it will set input route (dst->out = ip_rt_bug) to skb for DESTUNREACH. For ICMP err triggered by locally generated packets, dst->dev of output route is loopback. Generally, xfrm relookup verification is not required on loopback interfaces (net.ipv4.conf.lo.disable_xfrm = 1). Skip icmp relookup for locally generated packets to fix it. Fixes: 8b7817f3a959 ("[IPSEC]: Add ICMP host relookup support") Signed-off-by: Dong Chenchen Reviewed-by: David Ahern Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20241127040850.1513135-1-dongchenchen2@huawei.com Signed-off-by: Jakub Kicinski Signed-off-by: Jiayuan Chen Signed-off-by: Sasha Levin

ipv4: icmp: validate reply type before using icmp_pointers

2026-05-17T15:13:30+00:00

commit 67bf002a2d7387a6312138210d0bd06e3cf4879b upstream. Extended echo replies use ICMP_EXT_ECHOREPLY as the outbound reply type. That value is outside the range covered by icmp_pointers[], which only describes the traditional ICMP types up to NR_ICMP_TYPES. Avoid consulting icmp_pointers[] for reply types outside that range, and use array_index_nospec() for the remaining in-range lookup. Normal ICMP replies keep their existing behavior unchanged. Fixes: d329ea5bd884 ("icmp: add response to RFC 8335 PROBE messages") Cc: stable@kernel.org Reported-by: Yuan Tan Reported-by: Yifan Wu Reported-by: Juefei Pu Reported-by: Xin Liu Signed-off-by: Ruide Cao Signed-off-by: Ren Wei Reviewed-by: Simon Horman Link: https://patch.msgid.link/0dace90c01a5978e829ca741ef684dbd7304ce62.1776628519.git.caoruide123@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

ipv4: icmp: fix null-ptr-deref in icmp_build_probe()

2026-04-27T13:23:27+00:00

[ Upstream commit fde29fd9349327acc50d19a0b5f3d5a6c964dfd8 ] ipv6_stub->ipv6_dev_find() may return ERR_PTR(-EAFNOSUPPORT) when the IPv6 stack is not active (CONFIG_IPV6=m and not loaded), and passing this error pointer to dev_hold() will cause a kernel crash with null-ptr-deref. Instead, silently discard the request. RFC 8335 does not appear to define a specific response for the case where an IPv6 interface identifier is syntactically valid but the implementation cannot perform the lookup at runtime, and silently dropping the request may safer than misreporting "No Such Interface". Fixes: d329ea5bd884 ("icmp: add response to RFC 8335 PROBE messages") Signed-off-by: Yiqi Sun Link: https://patch.msgid.link/20260402070419.2291578-1-sunyiqixm@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

icmp: fix NULL pointer dereference in icmp_tag_validation()

2026-03-25T10:06:09+00:00

[ Upstream commit 614aefe56af8e13331e50220c936fc0689cf5675 ] icmp_tag_validation() unconditionally dereferences the result of rcu_dereference(inet_protos[proto]) without checking for NULL. The inet_protos[] array is sparse -- only about 15 of 256 protocol numbers have registered handlers. When ip_no_pmtu_disc is set to 3 (hardened PMTU mode) and the kernel receives an ICMP Fragmentation Needed error with a quoted inner IP header containing an unregistered protocol number, the NULL dereference causes a kernel panic in softirq context. Oops: general protection fault, probably for non-canonical address 0xdffffc0000000002: 0000 [#1] SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017] RIP: 0010:icmp_unreach (net/ipv4/icmp.c:1085 net/ipv4/icmp.c:1143) Call Trace: icmp_rcv (net/ipv4/icmp.c:1527) ip_protocol_deliver_rcu (net/ipv4/ip_input.c:207) ip_local_deliver_finish (net/ipv4/ip_input.c:242) ip_local_deliver (net/ipv4/ip_input.c:262) ip_rcv (net/ipv4/ip_input.c:573) __netif_receive_skb_one_core (net/core/dev.c:6164) process_backlog (net/core/dev.c:6628) handle_softirqs (kernel/softirq.c:561) Add a NULL check before accessing icmp_strict_tag_validation. If the protocol has no registered handler, return false since it cannot perform strict tag validation. Fixes: 8ed1dc44d3e9 ("ipv4: introduce hardened ip_no_pmtu_disc mode") Reported-by: Xiang Mei Signed-off-by: Weiming Shi Link: https://patch.msgid.link/20260318130558.1050247-4-bestswngs@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

icmp: prevent possible overflow in icmp_global_allow()

2026-03-04T12:20:21+00:00

[ Upstream commit 034bbd806298e9ba4197dd1587b0348ee30996ea ] Following expression can overflow if sysctl_icmp_msgs_per_sec is big enough. sysctl_icmp_msgs_per_sec * delta / HZ; Fixes: 4cdf507d5452 ("icmp: add a global rate limitation") Signed-off-by: Eric Dumazet Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20260216142832.3834174-2-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

icmp: icmp_msgs_per_sec and icmp_msgs_burst sysctls become per netns

2026-03-04T12:20:21+00:00

[ Upstream commit f17bf505ff89595df5147755e51441632a5dc563 ] Previous patch made ICMP rate limits per netns, it makes sense to allow each netns to change the associated sysctl. Signed-off-by: Eric Dumazet Reviewed-by: David Ahern Link: https://patch.msgid.link/20240829144641.3880376-4-edumazet@google.com Signed-off-by: Jakub Kicinski Stable-dep-of: 034bbd806298 ("icmp: prevent possible overflow in icmp_global_allow()") Signed-off-by: Sasha Levin

icmp: move icmp_global.credit and icmp_global.stamp to per netns storage

2026-03-04T12:20:21+00:00

[ Upstream commit b056b4cd9178f7a1d5d57f7b48b073c29729ddaa ] Host wide ICMP ratelimiter should be per netns, to provide better isolation. Following patch in this series makes the sysctl per netns. Signed-off-by: Eric Dumazet Reviewed-by: David Ahern Link: https://patch.msgid.link/20240829144641.3880376-3-edumazet@google.com Signed-off-by: Jakub Kicinski Stable-dep-of: 034bbd806298 ("icmp: prevent possible overflow in icmp_global_allow()") Signed-off-by: Sasha Levin

xfrm: fix ip_rt_bug race in icmp_route_lookup reverse path

2026-03-04T12:19:53+00:00

[ Upstream commit 81b84de32bb27ae1ae2eb9acf0420e9d0d14bf00 ] icmp_route_lookup() performs multiple route lookups to find a suitable route for sending ICMP error messages, with special handling for XFRM (IPsec) policies. The lookup sequence is: 1. First, lookup output route for ICMP reply (dst = original src) 2. Pass through xfrm_lookup() for policy check 3. If blocked (-EPERM) or dst is not local, enter "reverse path" 4. In reverse path, call xfrm_decode_session_reverse() to get fl4_dec which reverses the original packet's flow (saddr<->daddr swapped) 5. If fl4_dec.saddr is local (we are the original destination), use __ip_route_output_key() for output route lookup 6. If fl4_dec.saddr is NOT local (we are a forwarding node), use ip_route_input() to simulate the reverse packet's input path 7. Finally, pass rt2 through xfrm_lookup() with XFRM_LOOKUP_ICMP flag The bug occurs in step 6: ip_route_input() is called with fl4_dec.daddr (original packet's source) as destination. If this address becomes local between the initial check and ip_route_input() call (e.g., due to concurrent "ip addr add"), ip_route_input() returns a LOCAL route with dst.output set to ip_rt_bug. This route is then used for ICMP output, causing dst_output() to call ip_rt_bug(), triggering a WARN_ON: ------------[ cut here ]------------ WARNING: net/ipv4/route.c:1275 at ip_rt_bug+0x21/0x30, CPU#1 Call Trace: ip_push_pending_frames+0x202/0x240 icmp_push_reply+0x30d/0x430 __icmp_send+0x1149/0x24f0 ip_options_compile+0xa2/0xd0 ip_rcv_finish_core+0x829/0x1950 ip_rcv+0x2d7/0x420 __netif_receive_skb_one_core+0x185/0x1f0 netif_receive_skb+0x90/0x450 tun_get_user+0x3413/0x3fb0 tun_chr_write_iter+0xe4/0x220 ... Fix this by checking rt2->rt_type after ip_route_input(). If it's RTN_LOCAL, the route cannot be used for output, so treat it as an error. The reproducer requires kernel modification to widen the race window, making it unsuitable as a selftest. It is available at: https://gist.github.com/mrpre/eae853b72ac6a750f5d45d64ddac1e81 Reported-by: syzbot+e738404dcd14b620923c@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/000000000000b1060905eada8881@google.com/T/ Closes: https://lore.kernel.org/r/20260128090523.356953-1-jiayuan.chen@linux.dev Fixes: 8b7817f3a959 ("[IPSEC]: Add ICMP host relookup support") Signed-off-by: Jiayuan Chen Signed-off-by: Jiayuan Chen Link: https://patch.msgid.link/20260206050220.59642-1-jiayuan.chen@linux.dev Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin

net: Switch to skb_dstref_steal/skb_dstref_restore for ip_route_input callers

2026-03-04T12:19:53+00:00

[ Upstream commit e97e6a1830ddb5885ba312e56b6fa3aa39b5f47e ] Going forward skb_dst_set will assert that skb dst_entry is empty during skb_dst_set. skb_dstref_steal is added to reset existing entry without doing refcnt. skb_dstref_restore should be used to restore the previous entry. Convert icmp_route_lookup and ip_options_rcv_srr to these helpers. Add extra call to skb_dstref_reset to icmp_route_lookup to clear the ip_route_input entry. Signed-off-by: Stanislav Fomichev Link: https://patch.msgid.link/20250818154032.3173645-5-sdf@fomichev.me Signed-off-by: Jakub Kicinski Stable-dep-of: 81b84de32bb2 ("xfrm: fix ip_rt_bug race in icmp_route_lookup reverse path") Signed-off-by: Sasha Levin

inet: RAW sockets using IPPROTO_RAW MUST drop incoming ICMP

2026-03-04T12:19:50+00:00

[ Upstream commit c89477ad79446867394360b29bb801010fc3ff22 ] Yizhou Zhao reported that simply having one RAW socket on protocol IPPROTO_RAW (255) was dangerous. socket(AF_INET, SOCK_RAW, 255); A malicious incoming ICMP packet can set the protocol field to 255 and match this socket, leading to FNHE cache changes. inner = IP(src="192.168.2.1", dst="8.8.8.8", proto=255)/Raw("TEST") pkt = IP(src="192.168.1.1", dst="192.168.2.1")/ICMP(type=3, code=4, nexthopmtu=576)/inner "man 7 raw" states: A protocol of IPPROTO_RAW implies enabled IP_HDRINCL and is able to send any IP protocol that is specified in the passed header. Receiving of all IP protocols via IPPROTO_RAW is not possible using raw sockets. Make sure we drop these malicious packets. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: Yizhou Zhao Link: https://lore.kernel.org/netdev/20251109134600.292125-1-zhaoyz24@mails.tsinghua.edu.cn/ Signed-off-by: Eric Dumazet Reviewed-by: David Ahern Reviewed-by: Ido Schimmel Link: https://patch.msgid.link/20260203192509.682208-1-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin