kernel.git/net/ipv4, branch linux-5.10.y

ipv4: fib: Annotate access to struct fib_alias.fa_state.

2026-03-04T12:20:02Z

[ Upstream commit 6e84fc395e90465f1418f582a9f7d53c87ab010e ] syzbot reported that struct fib_alias.fa_state can be modified locklessly by RCU readers. [0] Let's use READ_ONCE()/WRITE_ONCE() properly. [0]: BUG: KCSAN: data-race in fib_table_lookup / fib_table_lookup write to 0xffff88811b06a7fa of 1 bytes by task 4167 on cpu 0: fib_alias_accessed net/ipv4/fib_lookup.h:32 [inline] fib_table_lookup+0x361/0xd60 net/ipv4/fib_trie.c:1565 fib_lookup include/net/ip_fib.h:390 [inline] ip_route_output_key_hash_rcu+0x378/0x1380 net/ipv4/route.c:2814 ip_route_output_key_hash net/ipv4/route.c:2705 [inline] __ip_route_output_key include/net/route.h:169 [inline] ip_route_output_flow+0x65/0x110 net/ipv4/route.c:2932 udp_sendmsg+0x13c3/0x15d0 net/ipv4/udp.c:1450 inet_sendmsg+0xac/0xd0 net/ipv4/af_inet.c:859 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg net/socket.c:742 [inline] ____sys_sendmsg+0x53a/0x600 net/socket.c:2592 ___sys_sendmsg+0x195/0x1e0 net/socket.c:2646 __sys_sendmmsg+0x185/0x320 net/socket.c:2735 __do_sys_sendmmsg net/socket.c:2762 [inline] __se_sys_sendmmsg net/socket.c:2759 [inline] __x64_sys_sendmmsg+0x57/0x70 net/socket.c:2759 x64_sys_call+0x1e28/0x3000 arch/x86/include/generated/asm/syscalls_64.h:308 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xc0/0x2a0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f read to 0xffff88811b06a7fa of 1 bytes by task 4168 on cpu 1: fib_alias_accessed net/ipv4/fib_lookup.h:31 [inline] fib_table_lookup+0x338/0xd60 net/ipv4/fib_trie.c:1565 fib_lookup include/net/ip_fib.h:390 [inline] ip_route_output_key_hash_rcu+0x378/0x1380 net/ipv4/route.c:2814 ip_route_output_key_hash net/ipv4/route.c:2705 [inline] __ip_route_output_key include/net/route.h:169 [inline] ip_route_output_flow+0x65/0x110 net/ipv4/route.c:2932 udp_sendmsg+0x13c3/0x15d0 net/ipv4/udp.c:1450 inet_sendmsg+0xac/0xd0 net/ipv4/af_inet.c:859 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg net/socket.c:742 [inline] ____sys_sendmsg+0x53a/0x600 net/socket.c:2592 ___sys_sendmsg+0x195/0x1e0 net/socket.c:2646 __sys_sendmmsg+0x185/0x320 net/socket.c:2735 __do_sys_sendmmsg net/socket.c:2762 [inline] __se_sys_sendmmsg net/socket.c:2759 [inline] __x64_sys_sendmmsg+0x57/0x70 net/socket.c:2759 x64_sys_call+0x1e28/0x3000 arch/x86/include/generated/asm/syscalls_64.h:308 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xc0/0x2a0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f value changed: 0x00 -> 0x01 Reported by Kernel Concurrency Sanitizer on: CPU: 1 UID: 0 PID: 4168 Comm: syz.4.206 Not tainted syzkaller #0 PREEMPT(voluntary) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Reported-by: syzbot+d24f940f770afda885cf@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/69783ead.050a0220.c9109.0013.GAE@google.com/ Signed-off-by: Kuniyuki Iwashima Reviewed-by: Simon Horman Link: https://patch.msgid.link/20260127043528.514160-1-kuniyu@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

tcp: tcp_tx_timestamp() must look at the rtx queue

2026-03-04T12:19:34Z

[ Upstream commit 838eb9687691d29915797a885b861fd09353386e ] tcp_tx_timestamp() is only called at the end of tcp_sendmsg_locked() before the final tcp_push(). By the time it is called, it is possible all the copied data has been sent already (transmit queue is empty). If this is the case, use the last skb in the rtx queue. Fixes: 75c119afe14f ("tcp: implement rb-tree based retransmit queue") Signed-off-by: Eric Dumazet Reviewed-by: Jason Xing Link: https://patch.msgid.link/20260127123828.4098577-2-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

fou: Don't allow 0 for FOU_ATTR_IPPROTO.

2026-02-06T15:40:04Z

[ Upstream commit 7a9bc9e3f42391e4c187e099263cf7a1c4b69ff5 ] fou_udp_recv() has the same problem mentioned in the previous patch. If FOU_ATTR_IPPROTO is set to 0, skb is not freed by fou_udp_recv() nor "resubmit"-ted in ip_protocol_deliver_rcu(). Let's forbid 0 for FOU_ATTR_IPPROTO. Fixes: 23461551c0062 ("fou: Support for foo-over-udp RX path") Signed-off-by: Kuniyuki Iwashima Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20260115172533.693652-4-kuniyu@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net: fou: use policy and operation tables generated from the spec

2026-02-06T15:40:04Z

[ Upstream commit 1d562c32e4392cc091c940918ee1ffd7bfcb9e96 ] Generate and plug in the spec-based tables. A little bit of renaming is needed in the FOU code. Acked-by: Stanislav Fomichev Signed-off-by: Jakub Kicinski Signed-off-by: Paolo Abeni Stable-dep-of: 7a9bc9e3f423 ("fou: Don't allow 0 for FOU_ATTR_IPPROTO.") Signed-off-by: Sasha Levin

net: fou: rename the source for linking

2026-02-06T15:40:03Z

[ Upstream commit 08d323234d10eab077cbf0093eeb5991478a261a ] We'll need to link two objects together to form the fou module. This means the source can't be called fou, the build system expects fou.o to be the combined object. Acked-by: Stanislav Fomichev Signed-off-by: Jakub Kicinski Signed-off-by: Paolo Abeni Stable-dep-of: 7a9bc9e3f423 ("fou: Don't allow 0 for FOU_ATTR_IPPROTO.") Signed-off-by: Sasha Levin

gue: Fix skb memleak with inner IP protocol 0.

2026-02-06T15:40:03Z

[ Upstream commit 9a56796ad258786d3624eef5aefba394fc9bdded ] syzbot reported skb memleak below. [0] The repro generated a GUE packet with its inner protocol 0. gue_udp_recv() returns -guehdr->proto_ctype for "resubmit" in ip_protocol_deliver_rcu(), but this only works with non-zero protocol number. Let's drop such packets. Note that 0 is a valid number (IPv6 Hop-by-Hop Option). I think it is not practical to encap HOPOPT in GUE, so once someone starts to complain, we could pass down a resubmit flag pointer to distinguish two zeros from the upper layer: * no error * resubmit HOPOPT [0] BUG: memory leak unreferenced object 0xffff888109695a00 (size 240): comm "syz.0.17", pid 6088, jiffies 4294943096 hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 40 c2 10 81 88 ff ff 00 00 00 00 00 00 00 00 .@.............. backtrace (crc a84b336f): kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline] slab_post_alloc_hook mm/slub.c:4958 [inline] slab_alloc_node mm/slub.c:5263 [inline] kmem_cache_alloc_noprof+0x3b4/0x590 mm/slub.c:5270 __build_skb+0x23/0x60 net/core/skbuff.c:474 build_skb+0x20/0x190 net/core/skbuff.c:490 __tun_build_skb drivers/net/tun.c:1541 [inline] tun_build_skb+0x4a1/0xa40 drivers/net/tun.c:1636 tun_get_user+0xc12/0x2030 drivers/net/tun.c:1770 tun_chr_write_iter+0x71/0x120 drivers/net/tun.c:1999 new_sync_write fs/read_write.c:593 [inline] vfs_write+0x45d/0x710 fs/read_write.c:686 ksys_write+0xa7/0x170 fs/read_write.c:738 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xa4/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Fixes: 37dd0247797b1 ("gue: Receive side for Generic UDP Encapsulation") Reported-by: syzbot+4d8c7d16b0e95c0d0f0d@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/6965534b.050a0220.38aacd.0001.GAE@google.com/ Signed-off-by: Kuniyuki Iwashima Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20260115172533.693652-2-kuniyu@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

ipv4: ip_gre: make ipgre_header() robust

2026-02-06T15:39:58Z

[ Upstream commit e67c577d89894811ce4dcd1a9ed29d8b63476667 ] Analog to commit db5b4e39c4e6 ("ip6_gre: make ip6gre_header() robust") Over the years, syzbot found many ways to crash the kernel in ipgre_header() [1]. This involves team or bonding drivers ability to dynamically change their dev->needed_headroom and/or dev->hard_header_len In this particular crash mld_newpack() allocated an skb with a too small reserve/headroom, and by the time mld_sendpack() was called, syzbot managed to attach an ipgre device. [1] skbuff: skb_under_panic: text:ffffffff89ea3cb7 len:2030915468 put:2030915372 head:ffff888058b43000 data:ffff887fdfa6e194 tail:0x120 end:0x6c0 dev:team0 kernel BUG at net/core/skbuff.c:213 ! Oops: invalid opcode: 0000 [#1] SMP KASAN PTI CPU: 1 UID: 0 PID: 1322 Comm: kworker/1:9 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025 Workqueue: mld mld_ifc_work RIP: 0010:skb_panic+0x157/0x160 net/core/skbuff.c:213 Call Trace: skb_under_panic net/core/skbuff.c:223 [inline] skb_push+0xc3/0xe0 net/core/skbuff.c:2641 ipgre_header+0x67/0x290 net/ipv4/ip_gre.c:897 dev_hard_header include/linux/netdevice.h:3436 [inline] neigh_connected_output+0x286/0x460 net/core/neighbour.c:1618 NF_HOOK_COND include/linux/netfilter.h:307 [inline] ip6_output+0x340/0x550 net/ipv6/ip6_output.c:247 NF_HOOK+0x9e/0x380 include/linux/netfilter.h:318 mld_sendpack+0x8d4/0xe60 net/ipv6/mcast.c:1855 mld_send_cr net/ipv6/mcast.c:2154 [inline] mld_ifc_work+0x83e/0xd60 net/ipv6/mcast.c:2693 process_one_work kernel/workqueue.c:3257 [inline] process_scheduled_works+0xad1/0x1770 kernel/workqueue.c:3340 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3421 kthread+0x711/0x8a0 kernel/kthread.c:463 ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 Fixes: c54419321455 ("GRE: Refactor GRE tunneling code.") Reported-by: syzbot+7c134e1c3aa3283790b9@syzkaller.appspotmail.com Closes: https://www.spinics.net/lists/netdev/msg1147302.html Signed-off-by: Eric Dumazet Link: https://patch.msgid.link/20260108190214.1667040-1-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

arp: do not assume dev_hard_header() does not change skb->head

2026-01-19T12:12:11Z

[ Upstream commit c92510f5e3f82ba11c95991824a41e59a9c5ed81 ] arp_create() is the only dev_hard_header() caller making assumption about skb->head being unchanged. A recent commit broke this assumption. Initialize @arp pointer after dev_hard_header() call. Fixes: db5b4e39c4e6 ("ip6_gre: make ip6gre_header() robust") Reported-by: syzbot+58b44a770a1585795351@syzkaller.appspotmail.com Signed-off-by: Eric Dumazet Link: https://patch.msgid.link/20260107212250.384552-1-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

inet: ping: Fix icmp out counting

2026-01-19T12:12:10Z

[ Upstream commit 4c0856c225b39b1def6c9a6bc56faca79550da13 ] When the ping program uses an IPPROTO_ICMP socket to send ICMP_ECHO messages, ICMP_MIB_OUTMSGS is counted twice. ping_v4_sendmsg ping_v4_push_pending_frames ip_push_pending_frames ip_finish_skb __ip_make_skb icmp_out_count(net, icmp_type); // first count icmp_out_count(sock_net(sk), user_icmph.type); // second count However, when the ping program uses an IPPROTO_RAW socket, ICMP_MIB_OUTMSGS is counted correctly only once. Therefore, the first count should be removed. Fixes: c319b4d76b9e ("net: ipv4: add IPPROTO_ICMP socket kind") Signed-off-by: yuan.gao Reviewed-by: Ido Schimmel Tested-by: Ido Schimmel Link: https://patch.msgid.link/20251224063145.3615282-1-yuan.gao@ucloud.cn Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

ipv4: Fix uninit-value access in __ip_make_skb()

2026-01-19T12:12:01Z

commit fc1092f51567277509563800a3c56732070b6aa4 upstream. KMSAN reported uninit-value access in __ip_make_skb() [1]. __ip_make_skb() tests HDRINCL to know if the skb has icmphdr. However, HDRINCL can cause a race condition. If calling setsockopt(2) with IP_HDRINCL changes HDRINCL while __ip_make_skb() is running, the function will access icmphdr in the skb even if it is not included. This causes the issue reported by KMSAN. Check FLOWI_FLAG_KNOWN_NH on fl4->flowi4_flags instead of testing HDRINCL on the socket. Also, fl4->fl4_icmp_type and fl4->fl4_icmp_code are not initialized. These are union in struct flowi4 and are implicitly initialized by flowi4_init_output(), but we should not rely on specific union layout. Initialize these explicitly in raw_sendmsg(). [1] BUG: KMSAN: uninit-value in __ip_make_skb+0x2b74/0x2d20 net/ipv4/ip_output.c:1481 __ip_make_skb+0x2b74/0x2d20 net/ipv4/ip_output.c:1481 ip_finish_skb include/net/ip.h:243 [inline] ip_push_pending_frames+0x4c/0x5c0 net/ipv4/ip_output.c:1508 raw_sendmsg+0x2381/0x2690 net/ipv4/raw.c:654 inet_sendmsg+0x27b/0x2a0 net/ipv4/af_inet.c:851 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg+0x274/0x3c0 net/socket.c:745 __sys_sendto+0x62c/0x7b0 net/socket.c:2191 __do_sys_sendto net/socket.c:2203 [inline] __se_sys_sendto net/socket.c:2199 [inline] __x64_sys_sendto+0x130/0x200 net/socket.c:2199 do_syscall_64+0xd8/0x1f0 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x6d/0x75 Uninit was created at: slab_post_alloc_hook mm/slub.c:3804 [inline] slab_alloc_node mm/slub.c:3845 [inline] kmem_cache_alloc_node+0x5f6/0xc50 mm/slub.c:3888 kmalloc_reserve+0x13c/0x4a0 net/core/skbuff.c:577 __alloc_skb+0x35a/0x7c0 net/core/skbuff.c:668 alloc_skb include/linux/skbuff.h:1318 [inline] __ip_append_data+0x49ab/0x68c0 net/ipv4/ip_output.c:1128 ip_append_data+0x1e7/0x260 net/ipv4/ip_output.c:1365 raw_sendmsg+0x22b1/0x2690 net/ipv4/raw.c:648 inet_sendmsg+0x27b/0x2a0 net/ipv4/af_inet.c:851 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg+0x274/0x3c0 net/socket.c:745 __sys_sendto+0x62c/0x7b0 net/socket.c:2191 __do_sys_sendto net/socket.c:2203 [inline] __se_sys_sendto net/socket.c:2199 [inline] __x64_sys_sendto+0x130/0x200 net/socket.c:2199 do_syscall_64+0xd8/0x1f0 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x6d/0x75 CPU: 1 PID: 15709 Comm: syz-executor.7 Not tainted 6.8.0-11567-gb3603fcb79b1 #25 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-1.fc39 04/01/2014 Fixes: 99e5acae193e ("ipv4: Fix potential uninit variable access bug in __ip_make_skb()") Reported-by: syzkaller Signed-off-by: Shigeru Yoshida Link: https://lore.kernel.org/r/20240430123945.2057348-1-syoshida@redhat.com Signed-off-by: Paolo Abeni [ Referred stable v6.1.y version of the patch to generate this one v6.1 link: https://github.com/gregkh/linux/commit/55bf541e018b76b3750cb6c6ea18c46e1ac5562e ] Signed-off-by: Shubham Kulkarni Signed-off-by: Greg Kroah-Hartman