syzbot

BUG: unable to handle page fault for address: ffffffffffffffec
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD cf35067 P4D cf35067 PUD cf37067 PMD 0 
Oops: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 6081 Comm: syz.3.45 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:ext4_ext_drop_refs fs/ext4/extents.c:119 [inline]
RIP: 0010:ext4_free_ext_path fs/ext4/extents.c:128 [inline]
RIP: 0010:ext4_ext_map_blocks+0x2d00/0x6800 fs/ext4/extents.c:4494
Code: 8b 7c 24 10 4d 85 ff 0f 84 bd 00 00 00 e8 78 dc 58 ff 49 8d 7f 08 48 89 f8 48 c1 e8 03 42 0f b6 04 30 84 c0 0f 85 3d 1e 00 00 <41> 0f b7 47 08 c1 e0 04 48 8d 04 40 48 89 44 24 10 4d 89 fc 49 8d
RSP: 0018:ffffc900042e7040 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff88807dae8000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffffffffffec
RBP: ffffc900042e72f0 R08: ffff88805b8745d3 R09: 1ffff1100b70e8ba
R10: dffffc0000000000 R11: ffffed100b70e8bb R12: 0000000000000000
R13: 1ffff9200085ce34 R14: dffffc0000000000 R15: ffffffffffffffe4
FS:  00007ff6920b16c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffec CR3: 000000001c365000 CR4: 00000000003506e0
Call Trace:
 <TASK>
 ext4_map_blocks+0x9e2/0x1b80 fs/ext4/inode.c:652
 _ext4_get_block+0x1eb/0x480 fs/ext4/inode.c:794
 ext4_get_block_unwritten+0x2e/0x100 fs/ext4/inode.c:827
 ext4_block_write_begin+0x55d/0x14f0 fs/ext4/inode.c:1091
 ext4_write_begin+0x5de/0x1070 fs/ext4/ext4_jbd2.h:-1
 ext4_da_write_begin+0x2df/0x9c0 fs/ext4/inode.c:2908
 generic_perform_write+0x2fe/0x5c0 mm/filemap.c:4031
 ext4_buffered_write_iter+0xcc/0x350 fs/ext4/file.c:299
 ext4_file_write_iter+0x1d9/0x1880 fs/ext4/file.c:-1
 call_write_iter include/linux/fs.h:2018 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x46c/0x990 fs/read_write.c:584
 ksys_pwrite64 fs/read_write.c:699 [inline]
 __do_sys_pwrite64 fs/read_write.c:709 [inline]
 __se_sys_pwrite64 fs/read_write.c:706 [inline]
 __x64_sys_pwrite64+0x19b/0x230 fs/read_write.c:706
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7ff69119c799
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ff6920b1028 EFLAGS: 00000246 ORIG_RAX: 0000000000000012
RAX: ffffffffffffffda RBX: 00007ff691415fa0 RCX: 00007ff69119c799
RDX: 000000000000fdef RSI: 0000200000000140 RDI: 0000000000000005
RBP: 00007ff691232c99 R08: 0000000000000000 R09: 0000000000000000
R10: 000000000000fecc R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff691416038 R14: 00007ff691415fa0 R15: 00007ffd4fe201c8
 </TASK>
Modules linked in:
CR2: ffffffffffffffec
---[ end trace 0000000000000000 ]---
RIP: 0010:ext4_ext_drop_refs fs/ext4/extents.c:119 [inline]
RIP: 0010:ext4_free_ext_path fs/ext4/extents.c:128 [inline]
RIP: 0010:ext4_ext_map_blocks+0x2d00/0x6800 fs/ext4/extents.c:4494
Code: 8b 7c 24 10 4d 85 ff 0f 84 bd 00 00 00 e8 78 dc 58 ff 49 8d 7f 08 48 89 f8 48 c1 e8 03 42 0f b6 04 30 84 c0 0f 85 3d 1e 00 00 <41> 0f b7 47 08 c1 e0 04 48 8d 04 40 48 89 44 24 10 4d 89 fc 49 8d
RSP: 0018:ffffc900042e7040 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff88807dae8000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffffffffffec
RBP: ffffc900042e72f0 R08: ffff88805b8745d3 R09: 1ffff1100b70e8ba
R10: dffffc0000000000 R11: ffffed100b70e8bb R12: 0000000000000000
R13: 1ffff9200085ce34 R14: dffffc0000000000 R15: ffffffffffffffe4
FS:  00007ff6920b16c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffec CR3: 000000001c365000 CR4: 00000000003506e0
----------------
Code disassembly (best guess):
   0:	8b 7c 24 10          	mov    0x10(%rsp),%edi
   4:	4d 85 ff             	test   %r15,%r15
   7:	0f 84 bd 00 00 00    	je     0xca
   d:	e8 78 dc 58 ff       	call   0xff58dc8a
  12:	49 8d 7f 08          	lea    0x8(%r15),%rdi
  16:	48 89 f8             	mov    %rdi,%rax
  19:	48 c1 e8 03          	shr    $0x3,%rax
  1d:	42 0f b6 04 30       	movzbl (%rax,%r14,1),%eax
  22:	84 c0                	test   %al,%al
  24:	0f 85 3d 1e 00 00    	jne    0x1e67
* 2a:	41 0f b7 47 08       	movzwl 0x8(%r15),%eax <-- trapping instruction
  2f:	c1 e0 04             	shl    $0x4,%eax
  32:	48 8d 04 40          	lea    (%rax,%rax,2),%rax
  36:	48 89 44 24 10       	mov    %rax,0x10(%rsp)
  3b:	4d 89 fc             	mov    %r15,%r12
  3e:	49                   	rex.WB
  3f:	8d                   	.byte 0x8d