Hello, syzbot found the following crash on: HEAD commit: 5b8b9d0c Merge branch 'akpm' (patches from Andrew) git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=13507b43e00000 kernel config: https://syzkaller.appspot.com/x/.config?x=23c5a352e32a1944 dashboard link: https://syzkaller.appspot.com/bug?extid=bca9799bf129256190da compiler: gcc (GCC) 9.0.0 20181231 (experimental) syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1620c007e00000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=117f975de00000 The bug was bisected to: commit 5f0663bb4a64f588f0a2dd6d1be68d40f9af0086 Author: Dan Williams <dan.j.williams@xxxxxxxxx> Date: Thu Dec 21 20:25:11 2017 +0000 ext4, dax: introduce ext4_dax_aops bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=11046b5de00000 final crash: https://syzkaller.appspot.com/x/report.txt?x=13046b5de00000 console output: https://syzkaller.appspot.com/x/log.txt?x=15046b5de00000 IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+bca9799bf129256190da@xxxxxxxxxxxxxxxxxxxxxxxxx Fixes: 5f0663bb4a64 ("ext4, dax: introduce ext4_dax_aops") BUG: kernel NULL pointer dereference, address: 0000000000000000 #PF: supervisor instruction fetch in kernel mode #PF: error_code(0x0010) - not-present page PGD 86de7067 P4D 86de7067 PUD 8eb7e067 PMD 0 Oops: 0010 [#1] PREEMPT SMP KASAN CPU: 0 PID: 8522 Comm: syz-executor124 Not tainted 5.6.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:0x0 Code: Bad RIP value. RSP: 0018:ffffc90004707a38 EFLAGS: 00010246 RAX: ffffffff883cb0a0 RBX: 0000000000000000 RCX: 0000000000000001 RDX: 0000000000000000 RSI: ffff8880880c68e0 RDI: ffff888098a0c300 RBP: ffff8880880c68e0 R08: 0000000000000000 R09: ffffc90004707ac0 R10: ffff88808ddee607 R11: ffffed1011bbdcc0 R12: 0000000000000001 R13: 0000000000000000 R14: 0000000000000000 R15: ffffc90004707d18 FS: 00007ff4c6fcc700(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffffffffd6 CR3: 0000000086de6000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: generic_perform_write+0x20a/0x4e0 mm/filemap.c:3302 ext4_buffered_write_iter+0x1f7/0x450 fs/ext4/file.c:270 ext4_file_write_iter+0x1ec/0x13f0 fs/ext4/file.c:642 call_write_iter include/linux/fs.h:1907 [inline] new_sync_write+0x4a2/0x700 fs/read_write.c:484 __vfs_write+0xc9/0x100 fs/read_write.c:497 vfs_write+0x268/0x5d0 fs/read_write.c:559 ksys_write+0x12d/0x250 fs/read_write.c:612 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295 entry_SYSCALL_64_after_hwframe+0x49/0xb3 RIP: 0033:0x44ecf9 Code: bd ca fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 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 0f 83 8b ca fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007ff4c6fcbce8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00000000006e79e8 RCX: 000000000044ecf9 RDX: 0000000000000001 RSI: 0000000020000080 RDI: 0000000000000003 RBP: 00000000006e79e0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006e79ec R13: 00007ffce52c26cf R14: 00007ff4c6fcc9c0 R15: 0000000000000000 Modules linked in: CR2: 0000000000000000 ---[ end trace a03cde52885aaa2a ]--- RIP: 0010:0x0 Code: Bad RIP value. RSP: 0018:ffffc90004707a38 EFLAGS: 00010246 RAX: ffffffff883cb0a0 RBX: 0000000000000000 RCX: 0000000000000001 RDX: 0000000000000000 RSI: ffff8880880c68e0 RDI: ffff888098a0c300 RBP: ffff8880880c68e0 R08: 0000000000000000 R09: ffffc90004707ac0 R10: ffff88808ddee607 R11: ffffed1011bbdcc0 R12: 0000000000000001 R13: 0000000000000000 R14: 0000000000000000 R15: ffffc90004707d18 FS: 00007ff4c6fcc700(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ff4c6f89db8 CR3: 0000000086de6000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 --- This bug is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. syzbot will keep track of this bug report. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. For information about bisection process see: https://goo.gl/tpsmEJ#bisection syzbot can test patches for this bug, for details see: https://goo.gl/tpsmEJ#testing-patches
