Hello, syzbot has tested the proposed patch but the reproducer is still triggering an issue: WARNING in __ip6_append_data l2tp_ip6_sendmsg() MAXPLEN check 0 4100 65575 40, 4 65536 l2tp_ip6_sendmsg() MAXPLEN check 4100 4100 65575 40, 0 65536 ------------[ cut here ]------------ WARNING: CPU: 0 PID: 5455 at net/ipv6/ip6_output.c:1812 __ip6_append_data.isra.0+0x1c6d/0x4900 net/ipv6/ip6_output.c:1812 Modules linked in: CPU: 0 PID: 5455 Comm: syz-executor.0 Not tainted 6.5.0-syzkaller-11938-g65d6e954e378-dirty #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/04/2023 RIP: 0010:__ip6_append_data.isra.0+0x1c6d/0x4900 net/ipv6/ip6_output.c:1812 Code: c4 f6 ff ff e8 84 d4 97 f8 49 8d 44 24 ff 48 89 44 24 68 49 8d 6c 24 07 e9 ab f6 ff ff 4c 8b b4 24 90 01 00 00 e8 63 d4 97 f8 <0f> 0b 48 8b 44 24 10 45 89 f4 48 8d 98 74 02 00 00 e8 4d d4 97 f8 RSP: 0018:ffffc90004f373b8 EFLAGS: 00010293 RAX: 0000000000000000 RBX: 0000000000001004 RCX: 0000000000000000 RDX: ffff888019e8bb80 RSI: ffffffff88efcf9d RDI: 0000000000000006 RBP: 0000000000001000 R08: 0000000000000006 R09: 0000000000001004 R10: 0000000000001000 R11: 0000000000000001 R12: 0000000000000001 R13: dffffc0000000000 R14: 0000000000001004 R15: ffff888027b1d640 FS: 00007feae40ff6c0(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f0f01e4e378 CR3: 000000007d467000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> ip6_append_data+0x1e6/0x510 net/ipv6/ip6_output.c:1909 l2tp_ip6_sendmsg+0xe0c/0x1ce0 net/l2tp/l2tp_ip6.c:633 inet_sendmsg+0x9d/0xe0 net/ipv4/af_inet.c:840 sock_sendmsg_nosec net/socket.c:730 [inline] sock_sendmsg+0xd9/0x180 net/socket.c:753 splice_to_socket+0xade/0x1010 fs/splice.c:881 do_splice_from fs/splice.c:933 [inline] direct_splice_actor+0x118/0x180 fs/splice.c:1142 splice_direct_to_actor+0x347/0xa30 fs/splice.c:1088 do_splice_direct+0x1af/0x280 fs/splice.c:1194 do_sendfile+0xb88/0x1390 fs/read_write.c:1254 __do_sys_sendfile64 fs/read_write.c:1322 [inline] __se_sys_sendfile64 fs/read_write.c:1308 [inline] __x64_sys_sendfile64+0x1d6/0x220 fs/read_write.c:1308 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7feae347cae9 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007feae40ff0c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000028 RAX: ffffffffffffffda RBX: 00007feae359bf80 RCX: 00007feae347cae9 RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000005 RBP: 00007feae34c847a R08: 0000000000000000 R09: 0000000000000000 R10: 000000010000a006 R11: 0000000000000246 R12: 0000000000000000 R13: 000000000000000b R14: 00007feae359bf80 R15: 00007ffc444d03c8 </TASK> Tested on: commit: 65d6e954 Merge tag 'gfs2-v6.5-rc5-fixes' of git://git... git tree: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git console output: https://syzkaller.appspot.com/x/log.txt?x=12133ac4680000 kernel config: https://syzkaller.appspot.com/x/.config?x=b273cdfbc13e9a4b dashboard link: https://syzkaller.appspot.com/bug?extid=62cbf263225ae13ff153 compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40 patch: https://syzkaller.appspot.com/x/patch.diff?x=139cae54680000
