------------[ cut here ]------------ WARNING: CPU: 0 PID: 355 at net/ipv4/tcp_input.c:2613 tcp_cwnd_reduction+0x321/0x380 net/ipv4/tcp_input.c:2613 Modules linked in: CPU: 0 PID: 355 Comm: syz-executor.1 Not tainted 5.15.0-syzkaller #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014 RIP: 0010:tcp_cwnd_reduction+0x321/0x380 net/ipv4/tcp_input.c:2613 Code: 80 09 00 00 48 83 c4 18 5b 5d 41 5c 41 5d 41 5e 41 5f e9 32 79 d0 f9 e8 2d 79 d0 f9 41 39 ec 41 0f 4e ec eb 89 e8 1f 79 d0 f9 <0f> 0b eb d6 e8 16 a8 16 fa e9 38 fd ff ff e8 0c a8 16 fa e9 20 fe RSP: 0018:ffffc90002d776e8 EFLAGS: 00010206 RAX: 0000000000005a10 RBX: ffff888025ad4e40 RCX: ffffc90002e69000 RDX: 0000000000040000 RSI: ffffffff87a68401 RDI: 0000000000000003 RBP: 000000000000000a R08: 0000000000000000 R09: 0000000000000000 R10: ffffffff87a68158 R11: 0000000000000000 R12: 000000000000000a R13: 0000000000000000 R14: 0000000000000008 R15: ffff888025ad4e40 FS: 00007f8d29c70700(0000) GS:ffff88802ca00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b2d023000 CR3: 000000007051c000 CR4: 0000000000150ef0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600 Call Trace: tcp_cong_control net/ipv4/tcp_input.c:3485 [inline] tcp_ack+0x3fc1/0x5720 net/ipv4/tcp_input.c:3889 tcp_rcv_established+0x5d7/0x2130 net/ipv4/tcp_input.c:5936 tcp_v4_do_rcv+0x600/0x8d0 net/ipv4/tcp_ipv4.c:1716 sk_backlog_rcv include/net/sock.h:1030 [inline] __release_sock+0x134/0x3b0 net/core/sock.c:2768 __sk_flush_backlog+0x22/0x30 net/core/sock.c:2788 sk_flush_backlog include/net/sock.h:1117 [inline] tcp_sendmsg_locked+0x2676/0x2c60 net/ipv4/tcp.c:1276 tcp_sendmsg+0x2b/0x40 net/ipv4/tcp.c:1422 inet_sendmsg+0x99/0xe0 net/ipv4/af_inet.c:819 sock_sendmsg_nosec net/socket.c:704 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:724 __sys_sendto+0x21c/0x320 net/socket.c:2036 __do_sys_sendto net/socket.c:2048 [inline] __se_sys_sendto net/socket.c:2044 [inline] __x64_sys_sendto+0xdd/0x1b0 net/socket.c:2044 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f8d2c6faae9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f8d29c70188 EFLAGS: 00000246 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 00007f8d2c80df60 RCX: 00007f8d2c6faae9 RDX: ffffffffffffffef RSI: 0000000020d7cfcb RDI: 0000000000000003 RBP: 00007f8d2c754f6d R08: 0000000000000000 R09: 0000000000000053 R10: 000000000000001c R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffcd258606f R14: 00007f8d29c70300 R15: 0000000000022000