kernel/linux.git/net/ipv6/icmp.c, branch v7.0.10

ipv6: fix possible UAF in icmpv6_rcv()

2026-05-23T11:09:20+00:00

[ Upstream commit f996edd7615e686ada141b7f3395025729ff8ccb ] Caching saddr and daddr before pskb_pull() is problematic since skb->head can change. Remove these temporary variables: - We only access &ipv6_hdr(skb)->saddr and &ipv6_hdr(skb)->daddr when net_dbg_ratelimited() is called in the slow path. - Avoid potential future misuse after pskb_pull() call. Fixes: 4b3418fba0fe ("ipv6: icmp: include addresses in debug messages") Signed-off-by: Eric Dumazet Reviewed-by: Fernando Fernandez Mancera Reviewed-by: Joe Damato Reviewed-by: Ido Schimmel Link: https://patch.msgid.link/20260416103505.2380753-1-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

ipv6: icmp: clear skb2->cb[] in ip6_err_gen_icmpv6_unreach()

2026-03-28T03:22:46+00:00

Sashiko AI-review observed: In ip6_err_gen_icmpv6_unreach(), the skb is an outer IPv4 ICMP error packet where its cb contains an IPv4 inet_skb_parm. When skb is cloned into skb2 and passed to icmp6_send(), it uses IP6CB(skb2). IP6CB interprets the IPv4 inet_skb_parm as an inet6_skb_parm. The cipso offset in inet_skb_parm.opt directly overlaps with dsthao in inet6_skb_parm at offset 18. If an attacker sends a forged ICMPv4 error with a CIPSO IP option, dsthao would be a non-zero offset. Inside icmp6_send(), mip6_addr_swap() is called and uses ipv6_find_tlv(skb, opt->dsthao, IPV6_TLV_HAO). This would scan the inner, attacker-controlled IPv6 packet starting at that offset, potentially returning a fake TLV without checking if the remaining packet length can hold the full 18-byte struct ipv6_destopt_hao. Could mip6_addr_swap() then perform a 16-byte swap that extends past the end of the packet data into skb_shared_info? Should the cb array also be cleared in ip6_err_gen_icmpv6_unreach() and ip6ip6_err() to prevent this? This patch implements the first suggestion. I am not sure if ip6ip6_err() needs to be changed. A separate patch would be better anyway. Fixes: ca15a078bd90 ("sit: generate icmpv6 error when receiving icmpv4 error") Reported-by: Ido Schimmel Closes: https://sashiko.dev/#/patchset/20260326155138.2429480-1-edumazet%40google.com Signed-off-by: Eric Dumazet Cc: Oskar Kjos Reviewed-by: Ido Schimmel Link: https://patch.msgid.link/20260326202608.2976021-1-edumazet@google.com Signed-off-by: Jakub Kicinski

ipv6: icmp: icmpv6_xrlim_allow() optimization if net.ipv6.icmp.ratelimit is zero

2026-02-19T00:46:37+00:00

If net.ipv6.icmp.ratelimit is zero we do not have to call inet_getpeer_v6() and inet_peer_xrlim_allow(). Both can be very expensive under DDOS. Signed-off-by: Eric Dumazet Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20260216142832.3834174-6-edumazet@google.com Signed-off-by: Jakub Kicinski

ipv6: icmp: remove obsolete code in icmpv6_xrlim_allow()

2026-02-19T00:46:36+00:00

Following part was needed before the blamed commit, because inet_getpeer_v6() second argument was the prefix. /* Give more bandwidth to wider prefixes. */ if (rt->rt6i_dst.plen < 128) tmo >>= ((128 - rt->rt6i_dst.plen)>>5); Now inet_getpeer_v6() retrieves hosts, we need to remove @tmo adjustement or wider prefixes likes /24 allow 8x more ICMP to be sent for a given ratelimit. As we had this issue for a while, this patch changes net.ipv6.icmp.ratelimit default value from 1000ms to 100ms to avoid potential regressions. Also add a READ_ONCE() when reading net->ipv6.sysctl.icmpv6_time. Fixes: fd0273d7939f ("ipv6: Remove external dependency on rt6i_dst and rt6i_src") Signed-off-by: Eric Dumazet Reviewed-by: Kuniyuki Iwashima Cc: Martin KaFai Lau Link: https://patch.msgid.link/20260216142832.3834174-4-edumazet@google.com Signed-off-by: Jakub Kicinski

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

2026-02-11T14:14:35+00:00

Merge in late fixes in preparation for the net-next PR. Signed-off-by: Paolo Abeni

inet: RAW sockets using IPPROTO_RAW MUST drop incoming ICMP

2026-02-05T20:36:49+00:00

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

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

2026-01-30T01:28:54+00:00

Cross-merge networking fixes after downstream PR (net-6.19-rc8). No adjacent changes, conflicts: drivers/net/ethernet/spacemit/k1_emac.c 2c84959167d64 ("net: spacemit: Check for netif_carrier_ok() in emac_stats_update()") f66086798f91f ("net: spacemit: Remove broken flow control support") https://lore.kernel.org/aXjAqZA3iEWD_DGM@sirena.org.uk Signed-off-by: Jakub Kicinski

ipv6: use the right ifindex when replying to icmpv6 from localhost

2026-01-25T21:16:47+00:00

When replying to a ICMPv6 echo request that comes from localhost address the right output ifindex is 1 (lo) and not rt6i_idev dev index. Use the skb device ifindex instead. This fixes pinging to a local address from localhost source address. $ ping6 -I ::1 2001:1:1::2 -c 3 PING 2001:1:1::2 (2001:1:1::2) from ::1 : 56 data bytes 64 bytes from 2001:1:1::2: icmp_seq=1 ttl=64 time=0.037 ms 64 bytes from 2001:1:1::2: icmp_seq=2 ttl=64 time=0.069 ms 64 bytes from 2001:1:1::2: icmp_seq=3 ttl=64 time=0.122 ms 2001:1:1::2 ping statistics 3 packets transmitted, 3 received, 0% packet loss, time 2032ms rtt min/avg/max/mdev = 0.037/0.076/0.122/0.035 ms Fixes: 1b70d792cf67 ("ipv6: Use rt6i_idev index for echo replies to a local address") Signed-off-by: Fernando Fernandez Mancera Reviewed-by: David Ahern Link: https://patch.msgid.link/20260121194409.6749-1-fmancera@suse.de Signed-off-by: Jakub Kicinski

ipv6: annotate data-races over sysctl.flowlabel_reflect

2026-01-19T17:56:42+00:00

Add missing READ_ONCE() when reading ipv6.sysctl.flowlabel_reflect, as its value can be changed under us. Signed-off-by: Eric Dumazet Reviewed-by: Simon Horman Link: https://patch.msgid.link/20260115094141.3124990-6-edumazet@google.com Signed-off-by: Jakub Kicinski

ipv6: icmp: Add RFC 5837 support

2025-10-30T01:28:30+00:00

Add the ability to append the incoming IP interface information to ICMPv6 error messages in accordance with RFC 5837 and RFC 4884. This is required for more meaningful traceroute results in unnumbered networks. The feature is disabled by default and controlled via a new sysctl ("net.ipv6.icmp.errors_extension_mask") which accepts a bitmask of ICMP extensions to append to ICMP error messages. Currently, only a single value is supported, but the interface and the implementation should be able to support more extensions, if needed. Clone the skb and copy the relevant data portions before modifying the skb as the caller of icmp6_send() still owns the skb after the function returns. This should be fine since by default ICMP error messages are rate limited to 1000 per second and no more than 1 per second per specific host. Trim or pad the packet to 128 bytes before appending the ICMP extension structure in order to be compatible with legacy applications that assume that the ICMP extension structure always starts at this offset (the minimum length specified by RFC 4884). Since commit 20e1954fe238 ("ipv6: RFC 4884 partial support for SIT/GRE tunnels") it is possible for icmp6_send() to be called with an skb that already contains ICMP extensions. This can happen when we receive an ICMPv4 message with extensions from a tunnel and translate it to an ICMPv6 message towards an IPv6 host in the overlay network. I could not find an RFC that supports this behavior, but it makes sense to not overwrite the original extensions that were appended to the packet. Therefore, avoid appending extensions if the length field in the provided ICMPv6 header is already filled. Export netdev_copy_name() using EXPORT_IPV6_MOD_GPL() to make it available to IPv6 when it is built as a module. Reviewed-by: Petr Machata Reviewed-by: David Ahern Reviewed-by: Willem de Bruijn Signed-off-by: Ido Schimmel Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20251027082232.232571-3-idosch@nvidia.com Signed-off-by: Jakub Kicinski