bisecting fixing commit since 1434a3127887a7e708be5f4edd5e36d64d8622f8 building syzkaller on 3c7fef3361a6007112b26adc1c5a550189ef43fe testing commit 1434a3127887a7e708be5f4edd5e36d64d8622f8 with gcc (GCC) 10.2.1 20210217 kernel signature: 748a4c57c669c749792d994c76ea186d1f0c9fb3522a12d2adf7f199d32fffba all runs: crashed: divide error in tcp_reno_cong_avoid testing current HEAD 7426cedc7dad67bf3c71ea6cc29ab7822e1a453f testing commit 7426cedc7dad67bf3c71ea6cc29ab7822e1a453f with gcc (GCC) 10.2.1 20210217 kernel signature: add9d68b4365965f2974faa767db01619a587b52aa5a6888bcfdfbbf68a747b1 all runs: crashed: divide error in tcp_reno_cong_avoid revisions tested: 2, total time: 21m42.908678441s (build: 14m7.61652286s, test: 6m59.629002088s) the crash still happens on HEAD commit msg: Merge tag 'spi-fix-v5.13-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi crash: divide error in tcp_reno_cong_avoid divide error: 0000 [#1] PREEMPT SMP KASAN CPU: 0 PID: 10315 Comm: syz-executor.2 Not tainted 5.13.0-rc7-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:tcp_cong_avoid_ai net/ipv4/tcp_cong.c:420 [inline] RIP: 0010:tcp_reno_cong_avoid+0x1fd/0x2b0 net/ipv4/tcp_cong.c:450 Code: ab 40 09 00 00 44 89 e5 45 39 ec 41 0f 47 ed 85 c0 89 ab 38 09 00 00 0f 85 01 ff ff ff 48 83 c4 08 5b 5d 41 5c 41 5d c3 31 d2 f5 01 c1 89 93 3c 09 00 00 89 8b 38 09 00 00 e9 30 ff ff ff c7 RSP: 0018:ffffc9000b40f6b0 EFLAGS: 00010246 RAX: 0000000000000011 RBX: ffff88802cdebac0 RCX: 0000000000000001 RDX: 0000000000000000 RSI: 000000001a82ccd9 RDI: ffff88802cdec3fc RBP: 0000000000000000 R08: dffffc0000000000 R09: 000000006e44e00f R10: 00000000c6b4b947 R11: ffff88802cdec2a8 R12: 0000000000000000 R13: 00000000ffffffff R14: 0000000000000011 R15: ffff88802cdec3f8 FS: 00007f1012a7f700(0000) GS:ffff8880b9e00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000005680c0 CR3: 0000000042c9c000 CR4: 00000000001506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: tcp_cdg_cong_avoid+0x47d/0x1410 net/ipv4/tcp_cdg.c:293 tcp_cong_avoid net/ipv4/tcp_input.c:3084 [inline] tcp_cong_control net/ipv4/tcp_input.c:3442 [inline] tcp_ack+0x30dd/0x5640 net/ipv4/tcp_input.c:3843 tcp_rcv_established+0x49f/0x1f50 net/ipv4/tcp_input.c:5872 tcp_v4_do_rcv+0x4f0/0x750 net/ipv4/tcp_ipv4.c:1694 sk_backlog_rcv include/net/sock.h:1020 [inline] __release_sock+0x113/0x360 net/core/sock.c:2558 __sk_flush_backlog+0x1d/0x30 net/core/sock.c:2578 sk_flush_backlog include/net/sock.h:1107 [inline] tcp_sendmsg_locked+0x237d/0x2f20 net/ipv4/tcp.c:1305 tcp_sendmsg+0x23/0x40 net/ipv4/tcp.c:1458 sock_sendmsg_nosec net/socket.c:654 [inline] sock_sendmsg+0xab/0xe0 net/socket.c:674 __sys_sendto+0x1a4/0x270 net/socket.c:1964 __do_sys_sendto net/socket.c:1976 [inline] __se_sys_sendto net/socket.c:1972 [inline] __x64_sys_sendto+0xd8/0x1b0 net/socket.c:1972 do_syscall_64+0x3a/0xb0 arch/x86/entry/common.c:47 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x4665d9 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:00007f1012a7f188 EFLAGS: 00000246 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 000000000056bf80 RCX: 00000000004665d9 RDX: 00000000fffffd46 RSI: 0000000020000240 RDI: 0000000000000004 RBP: 00000000004bfcb9 R08: 0000000000000000 R09: 00000000000001f4 R10: 00000000000081f4 R11: 0000000000000246 R12: 000000000056bf80 R13: 00007ffecca55eff R14: 00007f1012a7f300 R15: 0000000000022000 Modules linked in: ---[ end trace 3b713a0069e0be19 ]--- RIP: 0010:tcp_cong_avoid_ai net/ipv4/tcp_cong.c:420 [inline] RIP: 0010:tcp_reno_cong_avoid+0x1fd/0x2b0 net/ipv4/tcp_cong.c:450 Code: ab 40 09 00 00 44 89 e5 45 39 ec 41 0f 47 ed 85 c0 89 ab 38 09 00 00 0f 85 01 ff ff ff 48 83 c4 08 5b 5d 41 5c 41 5d c3 31 d2 f5 01 c1 89 93 3c 09 00 00 89 8b 38 09 00 00 e9 30 ff ff ff c7 RSP: 0018:ffffc9000b40f6b0 EFLAGS: 00010246 RAX: 0000000000000011 RBX: ffff88802cdebac0 RCX: 0000000000000001 RDX: 0000000000000000 RSI: 000000001a82ccd9 RDI: ffff88802cdec3fc RBP: 0000000000000000 R08: dffffc0000000000 R09: 000000006e44e00f R10: 00000000c6b4b947 R11: ffff88802cdec2a8 R12: 0000000000000000 R13: 00000000ffffffff R14: 0000000000000011 R15: ffff88802cdec3f8 FS: 00007f1012a7f700(0000) GS:ffff8880b9f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000556b4ee1cd67 CR3: 0000000042c9c000 CR4: 00000000001506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400