syzbot has found a reproducer for the following issue on: HEAD commit: a2c63a3f3d68 Merge tag 'bcachefs-2024-04-22' of https://ev.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=11623dfd180000 kernel config: https://syzkaller.appspot.com/x/.config?x=545d4b3e07d6ccbc dashboard link: https://syzkaller.appspot.com/bug?extid=f3a09670f3d2a55b89b2 compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15ff809b180000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15aaab4f180000 Downloadable assets: disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7bc7510fe41f/non_bootable_disk-a2c63a3f.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/b64cb6a17a78/vmlinux-a2c63a3f.xz kernel image: https://storage.googleapis.com/syzbot-assets/8984e0f657fd/bzImage-a2c63a3f.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+f3a09670f3d2a55b89b2@xxxxxxxxxxxxxxxxxxxxxxxxx divide error: 0000 [#1] PREEMPT SMP KASAN NOPTI CPU: 3 PID: 5183 Comm: syz-executor293 Not tainted 6.9.0-rc5-syzkaller-00025-ga2c63a3f3d68 #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 RIP: 0010:netfs_submit_writethrough+0x201/0x280 fs/netfs/output.c:427 Code: fc ff df 48 89 fa 48 c1 ea 03 0f b6 14 02 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 04 84 d2 75 1a 8b 8b 0c 01 00 00 48 89 e8 31 d2 <48> f7 f1 48 89 c5 48 0f af e9 e9 1d ff ff ff e8 9b a3 b8 ff eb df RSP: 0018:ffffc90003477760 EFLAGS: 00010246 RAX: 0000000000001000 RBX: ffff88802d072c00 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff82304719 RDI: ffff88802d072d0c RBP: 0000000000001000 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000003 R12: 0000000000000000 R13: ffff8880324e05e0 R14: ffff88802d072d20 R15: 0000000000000000 FS: 0000555585aef480(0000) GS:ffff88806b500000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ffc516dc998 CR3: 0000000029bf4000 CR4: 0000000000350ef0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> netfs_advance_writethrough+0x13f/0x170 fs/netfs/output.c:449 netfs_perform_write+0x1b9f/0x26b0 fs/netfs/buffered_write.c:385 netfs_buffered_write_iter_locked+0x213/0x2c0 fs/netfs/buffered_write.c:454 netfs_file_write_iter+0x1e0/0x470 fs/netfs/buffered_write.c:493 v9fs_file_write_iter+0xa1/0x100 fs/9p/vfs_file.c:407 call_write_iter include/linux/fs.h:2110 [inline] do_iter_readv_writev+0x504/0x780 fs/read_write.c:741 vfs_writev+0x36f/0xdb0 fs/read_write.c:971 do_pwritev+0x1b2/0x260 fs/read_write.c:1072 __do_sys_pwritev2 fs/read_write.c:1131 [inline] __se_sys_pwritev2 fs/read_write.c:1122 [inline] __x64_sys_pwritev2+0xef/0x160 fs/read_write.c:1122 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcf/0x260 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fecc4c95b59 Code: 48 83 c4 28 c3 e8 67 17 00 00 0f 1f 80 00 00 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 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fff380e4b18 EFLAGS: 00000216 ORIG_RAX: 0000000000000148 RAX: ffffffffffffffda RBX: 00007fff380e4b30 RCX: 00007fecc4c95b59 RDX: 0000000000000001 RSI: 0000000020000240 RDI: 0000000000000003 RBP: 00007fff380e4b38 R08: 0000000000000000 R09: 0000000000000015 R10: 0000000000000000 R11: 0000000000000216 R12: 0000000000000000 R13: 00007fff380e4d98 R14: 0000000000000001 R15: 0000000000000001 </TASK> Modules linked in: ---[ end trace 0000000000000000 ]--- RIP: 0010:netfs_submit_writethrough+0x201/0x280 fs/netfs/output.c:427 Code: fc ff df 48 89 fa 48 c1 ea 03 0f b6 14 02 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 04 84 d2 75 1a 8b 8b 0c 01 00 00 48 89 e8 31 d2 <48> f7 f1 48 89 c5 48 0f af e9 e9 1d ff ff ff e8 9b a3 b8 ff eb df RSP: 0018:ffffc90003477760 EFLAGS: 00010246 RAX: 0000000000001000 RBX: ffff88802d072c00 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff82304719 RDI: ffff88802d072d0c RBP: 0000000000001000 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000003 R12: 0000000000000000 R13: ffff8880324e05e0 R14: ffff88802d072d20 R15: 0000000000000000 FS: 0000555585aef480(0000) GS:ffff88806b500000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ffc516dc998 CR3: 0000000029bf4000 CR4: 0000000000350ef0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 ---------------- Code disassembly (best guess), 2 bytes skipped: 0: df 48 89 fisttps -0x77(%rax) 3: fa cli 4: 48 c1 ea 03 shr $0x3,%rdx 8: 0f b6 14 02 movzbl (%rdx,%rax,1),%edx c: 48 89 f8 mov %rdi,%rax f: 83 e0 07 and $0x7,%eax 12: 83 c0 03 add $0x3,%eax 15: 38 d0 cmp %dl,%al 17: 7c 04 jl 0x1d 19: 84 d2 test %dl,%dl 1b: 75 1a jne 0x37 1d: 8b 8b 0c 01 00 00 mov 0x10c(%rbx),%ecx 23: 48 89 e8 mov %rbp,%rax 26: 31 d2 xor %edx,%edx * 28: 48 f7 f1 div %rcx <-- trapping instruction 2b: 48 89 c5 mov %rax,%rbp 2e: 48 0f af e9 imul %rcx,%rbp 32: e9 1d ff ff ff jmp 0xffffff54 37: e8 9b a3 b8 ff call 0xffb8a3d7 3c: eb df jmp 0x1d --- If you want syzbot to run the reproducer, reply with: #syz test: git://repo/address.git branch-or-commit-hash If you attach or paste a git patch, syzbot will apply it before testing.
