kernel/linux.git/net/ipv6, branch v6.6.155

ipv6: fix use-after-free in ip6_finish_output2()

2026-08-27T12:29:47+00:00

commit d0d48d999b0eee6bb176ef4e39d9be868fa80f7e upstream. ip6_finish_output2() caches a pointer to the IPv6 destination address (daddr) before invoking lwtunnel_xmit(). The LWT-BPF transmit path or other encapsulation operations within lwtunnel_xmit() can reallocate the skb head, freeing the memory that daddr points to. When lwtunnel_xmit() returns LWTUNNEL_XMIT_CONTINUE, the function continues to use the stale daddr pointer to compute the nexthop and to look up or create the neighbour entry. This results in a use-after-free read, which can leak sensitive kernel data, pollute the neighbour table with arbitrary values, misdirect traffic, or crash the system. Fix this by re-fetching the IPv6 header and the destination address pointer after lwtunnel_xmit() returns LWTUNNEL_XMIT_CONTINUE, ensuring that the subsequent nexthop computation and neighbour lookup operate on valid memory. Fixes: e415ed3a4b8b ("ipv6: use skb_expand_head in ip6_finish_output2") Cc: stable@vger.kernel.org Reported-by: Vega Signed-off-by: Luxiao Xu Signed-off-by: Ren Wei Reviewed-by: Vadim Fedorenko Reviewed-by: Ido Schimmel Link: https://patch.msgid.link/4aa3f53bc44e79572c6dd2340ec7b68ef1a3d87d.1786516730.git.rakukuip@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

ndisc: ndisc_send_redirect() cleanup

2026-08-27T12:29:46+00:00

commit 0784d83df3bfc977c13252a0599be924f0afa68d upstream. ndisc_send_redirect() is always called under rcu_read_lock(). It can use dev_net_rcu() and avoid one redundant rcu_read_lock()/rcu_read_unlock() pair. Signed-off-by: Eric Dumazet Reviewed-by: David Ahern Link: https://patch.msgid.link/20250214140705.2105890-1-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Li Xiasong Signed-off-by: Greg Kroah-Hartman

inet: frags: save a pair of atomic operations in reassembly

2026-08-27T12:29:44+00:00

[ Upstream commit ca0359df45a55a9eb4d6dc09a481064abf78320f ] As mentioned in commit 648700f76b03 ("inet: frags: use rhashtables for reassembly units"): A followup patch will even remove the refcount hold/release left from prior implementation and save a couple of atomic operations. This patch implements this idea, seven years later. Signed-off-by: Eric Dumazet Reviewed-by: Jacob Keller Link: https://patch.msgid.link/20250312082250.1803501-5-edumazet@google.com Signed-off-by: Paolo Abeni Stable-dep-of: 653d7ddf6cba ("inet: frags: publish queues before arming timer") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

inet: frags: change inet_frag_kill() to defer refcount updates

2026-08-27T12:29:44+00:00

[ Upstream commit eb0dfc0ef195a04e519b15d73cf25d8c25ee8df7 ] In the following patch, we no longer assume inet_frag_kill() callers own a reference. Consuming two refcounts from inet_frag_kill() would lead in UAF. Propagate the pointer to the refs that will be consumed later by the final inet_frag_putn() call. Signed-off-by: Eric Dumazet Link: https://patch.msgid.link/20250312082250.1803501-4-edumazet@google.com Signed-off-by: Paolo Abeni Stable-dep-of: 653d7ddf6cba ("inet: frags: publish queues before arming timer") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

inet: frags: add inet_frag_putn() helper

2026-08-27T12:29:44+00:00

[ Upstream commit ae2d90355aa5592b0e99c8bbb4c3fa1d8e205f1b ] inet_frag_putn() can release multiple references in one step. Use it in inet_frags_free_cb(). Replace inet_frag_put(X) with inet_frag_putn(X, 1) Signed-off-by: Eric Dumazet Link: https://patch.msgid.link/20250312082250.1803501-2-edumazet@google.com Signed-off-by: Paolo Abeni Stable-dep-of: 653d7ddf6cba ("inet: frags: publish queues before arming timer") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

ip6_tunnel: clear skb2->cb[] in ip6ip6_err()

2026-08-19T16:13:14+00:00

commit f803c086399da277b5d0ff36a107d0f162751800 upstream. ip6ip6_err() clones an outer IPv6 ICMP error skb, pulls it to the quoted inner IPv6 packet, and then passes the clone to icmpv6_send(). The clone still carries the outer packet's inet6_skb_parm in skb->cb. If the outer packet had a Home Address Option, IP6CB(skb2)->dsthao remains non-zero after skb_pull(). icmpv6_send() later calls mip6_addr_swap(), which uses that stale dsthao offset against the quoted inner packet. A malformed inner destination-options header can then make the HAO lookup and address swap run past the end of the quoted packet and corrupt skb_shared_info. Clear skb2->cb[] before pulling the quoted inner IPv6 packet so the reply path does not reuse metadata left by the outer IPv6 stack. Fixes: e490d1d85cf5 ("[IPV6] IP6TUNNEL: Split out generic routine in ip6ip6_err().") Cc: stable@vger.kernel.org Reported-by: Vega Signed-off-by: Zhiling Zou Reviewed-by: Ido Schimmel Link: https://patch.msgid.link/fe1a5e765fbca88d69391887f0ed26a19e3e4d39.1785736562.git.zhilinz@nebusec.ai Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

ipv6: fix Route Information option length validation

2026-08-19T16:13:13+00:00

commit d1ad8fb2ac6a1afb71dc22d9ae8efb4dda96c824 upstream. rt6_route_rcv() validates the Route Information option (RFC 4191) length against the prefix length, but both checks are off by one. rinfo->length is the ND option length in units of 8 octets and it *includes* the 8-byte option header, so an option carrying N bytes of prefix has length == 1 + N/8. RFC 4191 section 2.3 requires length 3 when Prefix Length is greater than 64, and 2 or 3 when it is greater than 0. The code accepts length >= 2 and length >= 1 respectively. ipv6_addr_prefix() then copies prefix_len/8 bytes out of rinfo->prefix, so a Router Advertisement with (prefix_len=128, length=2) or (prefix_len=64, length=1) makes the kernel read up to 8 bytes past the end of the option. Those bytes end up in the prefix of the route that gets installed, so they are visible to userspace: # RA with a Route Information option (prefix_len=128, length=2) # followed by a source link-layer address option, 01 01 de ad be ef ca fe $ ip -6 route show 2001:db8:dead:beef:101:dead:beef:cafe via fe80::1234 dev veth0 proto ra ^^^^^^^^^^^^^^^^^^ the next option, read out of bounds When the Route Information option is the last one in the packet, those eight bytes come from the skb tail room instead. Reject the option lengths RFC 4191 does not allow. Fixes: 70ceb4f53929 ("[IPV6]: ROUTE: Add experimental support for Route Information Option in RA (RFC4191).") Cc: stable@vger.kernel.org Signed-off-by: Yuejie Shi Reviewed-by: Ido Schimmel Link: https://patch.msgid.link/20260730035310.74584-1-syjcnss@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

net/tcp: Prepare tcp_md5sig_pool for TCP-AO

2026-08-19T16:13:08+00:00

[ Upstream commit 8c73b26315aadb82218360d0a9a05e515f6e4118 ] TCP-AO, similarly to TCP-MD5, needs to allocate tfms on a slow-path, which is setsockopt() and use crypto ahash requests on fast paths, which are RX/TX softirqs. Also, it needs a temporary/scratch buffer for preparing the hash. Rework tcp_md5sig_pool in order to support other hashing algorithms than MD5. It will make it possible to share pre-allocated crypto_ahash descriptors and scratch area between all TCP hash users. Internally tcp_sigpool calls crypto_clone_ahash() API over pre-allocated crypto ahash tfm. Kudos to Herbert, who provided this new crypto API. I was a little concerned over GFP_ATOMIC allocations of ahash and crypto_request in RX/TX (see tcp_sigpool_start()), so I benchmarked both "backends" with different algorithms, using patched version of iperf3[2]. On my laptop with i7-7600U @ 2.80GHz: clone-tfm per-CPU-requests TCP-MD5 2.25 Gbits/sec 2.30 Gbits/sec TCP-AO(hmac(sha1)) 2.53 Gbits/sec 2.54 Gbits/sec TCP-AO(hmac(sha512)) 1.67 Gbits/sec 1.64 Gbits/sec TCP-AO(hmac(sha384)) 1.77 Gbits/sec 1.80 Gbits/sec TCP-AO(hmac(sha224)) 1.29 Gbits/sec 1.30 Gbits/sec TCP-AO(hmac(sha3-512)) 481 Mbits/sec 480 Mbits/sec TCP-AO(hmac(md5)) 2.07 Gbits/sec 2.12 Gbits/sec TCP-AO(hmac(rmd160)) 1.01 Gbits/sec 995 Mbits/sec TCP-AO(cmac(aes128)) [not supporetd yet] 2.11 Gbits/sec So, it seems that my concerns don't have strong grounds and per-CPU crypto_request allocation can be dropped/removed from tcp_sigpool once ciphers get crypto_clone_ahash() support. [1]: https://lore.kernel.org/all/ZDefxOq6Ax0JeTRH@gondor.apana.org.au/T/#u [2]: https://github.com/0x7f454c46/iperf/tree/tcp-md5-ao Signed-off-by: Dmitry Safonov Reviewed-by: Steen Hegelund Acked-by: David Ahern Signed-off-by: David S. Miller Stable-dep-of: d0c80dbb9704 ("net/atm: fix slab-out-of-bounds read in vcc_setsockopt()") Signed-off-by: Sasha Levin

sysctl: treewide: constify ctl_table_header::ctl_table_arg

2026-08-09T18:22:03+00:00

[ Upstream commit bfa858f220ab8c950dd3e1310fee61950d0ecdae ] To be able to constify instances of struct ctl_tables it is necessary to remove ways through which non-const versions are exposed from the sysctl core. One of these is the ctl_table_arg member of struct ctl_table_header. Constify this reference as a prerequisite for the full constification of struct ctl_table instances. No functional change. Signed-off-by: Thomas Weißschuh Reviewed-by: Kees Cook Signed-off-by: David S. Miller Stable-dep-of: f8d5e7846025 ("sctp: avoid auth_enable sysctl UAF during netns teardown") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

net: ipv6: clear suppressed fib6 rule result

2026-08-09T18:21:54+00:00

commit 6aea62e433fe1b586202a5fee8b5807ce635e1d7 upstream. fib6_rule_suppress() drops a suppressed route with ip6_rt_put_flags(), but leaves res->rt6 pointing at the released rt6_info. If no later rule supplies a replacement, fib6_rule_lookup() still sees res.rt6 and returns that stale dst to its caller. A suppressing rule can therefore leak a released route back to rt6_lookup(), and the next put hits rcuref_put_slowpath() from dst_release(). Clear res->rt6 when suppressing the route so suppressed lookups fall through to the null dst instead of reusing the released one. Fixes: cdef485217d3 ("ipv6: fix memory leak in fib6_rule_suppress") Cc: stable@vger.kernel.org Reported-by: Vega Signed-off-by: Zhiling Zou Signed-off-by: Ren Wei Reviewed-by: Ido Schimmel Link: https://patch.msgid.link/4b8acb7787d54e440155585dd32ebdf0bef7d122.1784710966.git.zhilinz@nebusec.ai Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman