kernel/linux.git/net/l2tp, branch master

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

2026-04-09T20:20:59+00:00

Cross-merge networking fixes after downstream PR (net-7.0-rc8). Conflicts: net/ipv6/seg6_iptunnel.c c3812651b522f ("seg6: separate dst_cache for input and output paths in seg6 lwtunnel") 78723a62b969a ("seg6: add per-route tunnel source address") https://lore.kernel.org/adZhwtOYfo-0ImSa@sirena.org.uk net/ipv4/icmp.c fde29fd934932 ("ipv4: icmp: fix null-ptr-deref in icmp_build_probe()") d98adfbdd5c01 ("ipv4: drop ipv6_stub usage and use direct function calls") https://lore.kernel.org/adO3dccqnr6j-BL9@sirena.org.uk Adjacent changes: drivers/net/ethernet/stmicro/stmmac/chain_mode.c 51f4e090b9f8 ("net: stmmac: fix integer underflow in chain mode") 6b4286e05508 ("net: stmmac: rename STMMAC_GET_ENTRY() -> STMMAC_NEXT_ENTRY()") Signed-off-by: Jakub Kicinski

l2tp: Drop large packets with UDP encap

2026-04-09T08:19:05+00:00

syzbot reported a WARN on my patch series [1]. The actual issue is an overflow of 16-bit UDP length field, and it exists in the upstream code. My series added a debug WARN with an overflow check that exposed the issue, that's why syzbot tripped on my patches, rather than on upstream code. syzbot's repro: r0 = socket$pppl2tp(0x18, 0x1, 0x1) r1 = socket$inet6_udp(0xa, 0x2, 0x0) connect$inet6(r1, &(0x7f00000000c0)={0xa, 0x0, 0x0, @loopback, 0xfffffffc}, 0x1c) connect$pppl2tp(r0, &(0x7f0000000240)=@pppol2tpin6={0x18, 0x1, {0x0, r1, 0x4, 0x0, 0x0, 0x0, {0xa, 0x4e22, 0xffff, @ipv4={'\x00', '\xff\xff', @empty}}}}, 0x32) writev(r0, &(0x7f0000000080)=[{&(0x7f0000000000)="ee", 0x34000}], 0x1) It basically sends an oversized (0x34000 bytes) PPPoL2TP packet with UDP encapsulation, and l2tp_xmit_core doesn't check for overflows when it assigns the UDP length field. The value gets trimmed to 16 bites. Add an overflow check that drops oversized packets and avoids sending packets with trimmed UDP length to the wire. syzbot's stack trace (with my patch applied): len >= 65536u WARNING: ./include/linux/udp.h:38 at udp_set_len_short include/linux/udp.h:38 [inline], CPU#1: syz.0.17/5957 WARNING: ./include/linux/udp.h:38 at l2tp_xmit_core net/l2tp/l2tp_core.c:1293 [inline], CPU#1: syz.0.17/5957 WARNING: ./include/linux/udp.h:38 at l2tp_xmit_skb+0x1204/0x18d0 net/l2tp/l2tp_core.c:1327, CPU#1: syz.0.17/5957 Modules linked in: CPU: 1 UID: 0 PID: 5957 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 RIP: 0010:udp_set_len_short include/linux/udp.h:38 [inline] RIP: 0010:l2tp_xmit_core net/l2tp/l2tp_core.c:1293 [inline] RIP: 0010:l2tp_xmit_skb+0x1204/0x18d0 net/l2tp/l2tp_core.c:1327 Code: 0f 0b 90 e9 21 f9 ff ff e8 e9 05 ec f6 90 0f 0b 90 e9 8d f9 ff ff e8 db 05 ec f6 90 0f 0b 90 e9 cc f9 ff ff e8 cd 05 ec f6 90 <0f> 0b 90 e9 de fa ff ff 44 89 f1 80 e1 07 80 c1 03 38 c1 0f 8c 4f RSP: 0018:ffffc90003d67878 EFLAGS: 00010293 RAX: ffffffff8ad985e3 RBX: ffff8881a6400090 RCX: ffff8881697f0000 RDX: 0000000000000000 RSI: 0000000000034010 RDI: 000000000000ffff RBP: dffffc0000000000 R08: 0000000000000003 R09: 0000000000000004 R10: dffffc0000000000 R11: fffff520007acf00 R12: ffff8881baf20900 R13: 0000000000034010 R14: ffff8881a640008e R15: ffff8881760f7000 FS: 000055557e81f500(0000) GS:ffff8882a9467000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000200000033000 CR3: 00000001612f4000 CR4: 00000000000006f0 Call Trace: pppol2tp_sendmsg+0x40a/0x5f0 net/l2tp/l2tp_ppp.c:302 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg net/socket.c:742 [inline] sock_write_iter+0x503/0x550 net/socket.c:1195 do_iter_readv_writev+0x619/0x8c0 fs/read_write.c:-1 vfs_writev+0x33c/0x990 fs/read_write.c:1059 do_writev+0x154/0x2e0 fs/read_write.c:1105 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f636479c629 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffffd4241c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000014 RAX: ffffffffffffffda RBX: 00007f6364a15fa0 RCX: 00007f636479c629 RDX: 0000000000000001 RSI: 0000200000000080 RDI: 0000000000000003 RBP: 00007f6364832b39 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f6364a15fac R14: 00007f6364a15fa0 R15: 00007f6364a15fa0 [1]: https://lore.kernel.org/all/20260226201600.222044-1-alice.kernel@fastmail.im/ Fixes: 3557baabf280 ("[L2TP]: PPP over L2TP driver core") Reported-by: syzbot+ci3edea60a44225dec@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/69a1dfba.050a0220.3a55be.0026.GAE@google.com/ Signed-off-by: Alice Mikityanska Link: https://patch.msgid.link/20260403174949.843941-1-alice.kernel@fastmail.im Signed-off-by: Paolo Abeni

ipv6: convert CONFIG_IPV6 to built-in only and clean up Kconfigs

2026-03-29T18:21:22+00:00

Maintaining a modular IPv6 stack offers image size savings for specific setups, this benefit is outweighed by the architectural burden it imposes on the subsystems on implementation and maintenance. Therefore, drop it. Change CONFIG_IPV6 from tristate to bool. Remove all Kconfig dependencies across the tree that explicitly checked for IPV6=m. In addition, remove MODULE_DESCRIPTION(), MODULE_ALIAS(), MODULE_AUTHOR() and MODULE_LICENSE(). This is also replacing module_init() by device_initcall(). It is not possible to use fs_initcall() as IPv4 does because that creates a race condition on IPv6 addrconf. Finally, modify the default configs from CONFIG_IPV6=m to CONFIG_IPV6=y except for m68k as according to the bloat-o-meter the image is increasing by 330KB~ and that isn't acceptable. Instead, disable IPv6 on this architecture by default. This is aligned with m68k RAM requirements and recommendations [1]. [1] http://www.linux-m68k.org/faq/ram.html Signed-off-by: Fernando Fernandez Mancera Tested-by: Ricardo B. Marlière Acked-by: Krzysztof Kozlowski # arm64 Link: https://patch.msgid.link/20260325120928.15848-2-fmancera@suse.de Signed-off-by: Jakub Kicinski

l2tp: ppp: use max L2TP header size for PPP channel hdrlen

2026-03-19T10:00:04+00:00

chan.hdrlen is read once at channel registration by ppp_register_net_channel(), and used to set the PPP net device's hard_header_len. It was set to PPPOL2TP_L2TP_HDR_SIZE_NOSEQ (6), which is 4 bytes too small if sequence numbers are later enabled via setsockopt(PPPOL2TP_SO_SENDSEQ), causing unnecessary skb reallocations on the TX path. The setsockopt handler attempted to change netdev's hard_header_len by updating chan.hdrlen, but the PPP layer never re-reads it after the registration, so the update had no effect. To avoid the unnecessary reallocations, set chan.hdrlen to PPPOL2TP_L2TP_HDR_SIZE_SEQ (10) unconditionally at registration and remove the ineffective update in the setsockopt callback. Signed-off-by: Qingfang Deng Link: https://patch.msgid.link/20260317054141.524879-1-dqfext@gmail.com Signed-off-by: Paolo Abeni

net: remove addr_len argument of recvmsg() handlers

2026-03-03T02:17:17+00:00

Use msg->msg_namelen as a place holder instead of a temporary variable, notably in inet[6]_recvmsg(). This removes stack canaries and allows tail-calls. $ scripts/bloat-o-meter -t vmlinux.old vmlinux add/remove: 0/0 grow/shrink: 2/19 up/down: 26/-532 (-506) Function old new delta rawv6_recvmsg 744 767 +23 vsock_dgram_recvmsg 55 58 +3 vsock_connectible_recvmsg 50 47 -3 unix_stream_recvmsg 161 158 -3 unix_seqpacket_recvmsg 62 59 -3 unix_dgram_recvmsg 42 39 -3 tcp_recvmsg 546 543 -3 mptcp_recvmsg 1568 1565 -3 ping_recvmsg 806 800 -6 tcp_bpf_recvmsg_parser 983 974 -9 ip_recv_error 588 576 -12 ipv6_recv_rxpmtu 442 428 -14 udp_recvmsg 1243 1224 -19 ipv6_recv_error 1046 1024 -22 udpv6_recvmsg 1487 1461 -26 raw_recvmsg 465 437 -28 udp_bpf_recvmsg 1027 984 -43 sock_common_recvmsg 103 27 -76 inet_recvmsg 257 175 -82 inet6_recvmsg 257 175 -82 tcp_bpf_recvmsg 663 568 -95 Total: Before=25143834, After=25143328, chg -0.00% Signed-off-by: Eric Dumazet Reviewed-by: Willem de Bruijn Link: https://patch.msgid.link/20260227151120.1346573-1-edumazet@google.com Signed-off-by: Jakub Kicinski

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

2026-02-26T18:23:00+00:00

Cross-merge networking fixes after downstream PR (net-7.0-rc2). Conflicts: tools/testing/selftests/drivers/net/hw/rss_ctx.py 19c3a2a81d2b ("selftests: drv-net: rss: Generate unique ports for RSS context tests") ce5a0f4612db ("selftests: drv-net: rss_ctx: test RSS contexts persist after ifdown/up") include/net/inet_connection_sock.h 858d2a4f67ff6 ("tcp: fix potential race in tcp_v6_syn_recv_sock()") fcd3d039fab69 ("tcp: make tcp_v{4,6}_send_check() static") https://lore.kernel.org/aZ8PSFLzBrEU3I89@sirena.org.uk drivers/net/ethernet/mellanox/mlx5/core/en/xsk/setup.c drivers/net/ethernet/mellanox/mlx5/core/en/xsk/pool.c 69050f8d6d075 ("treewide: Replace kmalloc with kmalloc_obj for non-scalar types") bf4afc53b77ae ("Convert 'alloc_obj' family to use the new default GFP_KERNEL argument") 8a96b9144f18a ("net/mlx5e: Alloc xsk channel param out of mlx5e_open_xsk()") Adjacent changes: net/netfilter/ipvs/ip_vs_ctl.c c59bd9e62e06 ("ipvs: use more counters to avoid service lookups") bf4afc53b77a ("Convert 'alloc_obj' family to use the new default GFP_KERNEL argument") Signed-off-by: Jakub Kicinski

net: l2tp_eth: Replace deprecated strcpy with strscpy in l2tp_eth_create

2026-02-24T12:38:33+00:00

strcpy() has been deprecated [1] because it performs no bounds checking on the destination buffer, which can lead to buffer overflows. Replace it with the safer strscpy(). Use the two-argument version of strscpy() to copy 'cfg->ifname'. Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strcpy [1] Signed-off-by: Thorsten Blum Reviewed-by: Simon Horman Link: https://patch.msgid.link/20260223074137.321862-1-thorsten.blum@linux.dev Signed-off-by: Paolo Abeni

Convert 'alloc_obj' family to use the new default GFP_KERNEL argument

2026-02-22T01:09:51+00:00

This was done entirely with mindless brute force, using git grep -l '\

treewide: Replace kmalloc with kmalloc_obj for non-scalar types

2026-02-21T09:02:28+00:00

This is the result of running the Coccinelle script from scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to avoid scalar types (which need careful case-by-case checking), and instead replace kmalloc-family calls that allocate struct or union object instances: Single allocations: kmalloc(sizeof(TYPE), ...) are replaced with: kmalloc_obj(TYPE, ...) Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...) are replaced with: kmalloc_objs(TYPE, COUNT, ...) Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...) are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...) (where TYPE may also be *VAR) The resulting allocations no longer return "void *", instead returning "TYPE *". Signed-off-by: Kees Cook

l2tp: avoid one data-race in l2tp_tunnel_del_work()

2026-01-19T17:55:41+00:00

We should read sk->sk_socket only when dealing with kernel sockets. syzbot reported the following data-race: BUG: KCSAN: data-race in l2tp_tunnel_del_work / sk_common_release write to 0xffff88811c182b20 of 8 bytes by task 5365 on cpu 0: sk_set_socket include/net/sock.h:2092 [inline] sock_orphan include/net/sock.h:2118 [inline] sk_common_release+0xae/0x230 net/core/sock.c:4003 udp_lib_close+0x15/0x20 include/net/udp.h:325 inet_release+0xce/0xf0 net/ipv4/af_inet.c:437 __sock_release net/socket.c:662 [inline] sock_close+0x6b/0x150 net/socket.c:1455 __fput+0x29b/0x650 fs/file_table.c:468 ____fput+0x1c/0x30 fs/file_table.c:496 task_work_run+0x131/0x1a0 kernel/task_work.c:233 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] __exit_to_user_mode_loop kernel/entry/common.c:44 [inline] exit_to_user_mode_loop+0x1fe/0x740 kernel/entry/common.c:75 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline] syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline] do_syscall_64+0x1e1/0x2b0 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f read to 0xffff88811c182b20 of 8 bytes by task 827 on cpu 1: l2tp_tunnel_del_work+0x2f/0x1a0 net/l2tp/l2tp_core.c:1418 process_one_work kernel/workqueue.c:3257 [inline] process_scheduled_works+0x4ce/0x9d0 kernel/workqueue.c:3340 worker_thread+0x582/0x770 kernel/workqueue.c:3421 kthread+0x489/0x510 kernel/kthread.c:463 ret_from_fork+0x149/0x290 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 value changed: 0xffff88811b818000 -> 0x0000000000000000 Fixes: d00fa9adc528 ("l2tp: fix races with tunnel socket close") Reported-by: syzbot+7312e82745f7fa2526db@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/6968b029.050a0220.58bed.0016.GAE@google.com/T/#u Signed-off-by: Eric Dumazet Cc: James Chapman Reviewed-by: Guillaume Nault Link: https://patch.msgid.link/20260115092139.3066180-1-edumazet@google.com Signed-off-by: Jakub Kicinski