EXT4-fs error (device loop7): ext4_validate_block_bitmap:439: comm syz.7.1295: bg 0: block 112: padding at end of block bitmap is not set 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: 11114 Comm: syz.7.1295 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 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+0x2d21/0x6890 fs/ext4/extents.c:4513 Code: 8b 7c 24 18 4d 85 ff 0f 84 b1 e2 ff ff e8 87 ba 58 ff 49 8d 7f 08 48 89 f8 48 c1 e8 03 42 0f b6 04 30 84 c0 0f 85 e7 1d 00 00 <41> 0f b7 47 08 c1 e0 04 48 8d 04 40 48 89 44 24 10 49 8d 47 28 48 RSP: 0018:ffffc90005026d60 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 0000000000000007 RCX: ffff888023a9bc00 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffffffffffec RBP: ffffc90005027010 R08: ffffffff911bc607 R09: 1ffffffff22378c0 R10: dffffc0000000000 R11: fffffbfff22378c1 R12: 0000000000000001 R13: 1ffff92000a04dd8 R14: dffffc0000000000 R15: ffffffffffffffe4 FS: 00007fa74d2226c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffffffffec CR3: 0000000056230000 CR4: 00000000003506e0 Call Trace: ext4_map_blocks+0x9db/0x1a90 fs/ext4/inode.c:654 mpage_map_one_extent fs/ext4/inode.c:2204 [inline] mpage_map_and_submit_extent fs/ext4/inode.c:2257 [inline] ext4_do_writepages+0x1463/0x3990 fs/ext4/inode.c:2720 ext4_writepages+0x1dd/0x350 fs/ext4/inode.c:2809 do_writepages+0x351/0x590 mm/page-writeback.c:2575 filemap_fdatawrite_wbc+0x122/0x180 mm/filemap.c:390 __filemap_fdatawrite_range mm/filemap.c:423 [inline] file_write_and_wait_range+0x197/0x280 mm/filemap.c:781 generic_buffers_fsync_noflush+0x6f/0x160 fs/buffer.c:609 ext4_fsync_nojournal fs/ext4/fsync.c:92 [inline] ext4_sync_file+0x460/0xd50 fs/ext4/fsync.c:163 generic_write_sync include/linux/fs.h:2651 [inline] ext4_buffered_write_iter+0x2c0/0x350 fs/ext4/file.c:305 ext4_file_write_iter+0x1e7/0x1980 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+0x474/0x9a0 fs/read_write.c:584 ksys_write+0x151/0x260 fs/read_write.c:637 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7fa74c39ce59 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:00007fa74d222028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007fa74c616090 RCX: 00007fa74c39ce59 RDX: 0000000000001006 RSI: 0000200000001440 RDI: 0000000000000010 RBP: 00007fa74c432e6f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fa74c616128 R14: 00007fa74c616090 R15: 00007ffcecb64f48 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+0x2d21/0x6890 fs/ext4/extents.c:4513 Code: 8b 7c 24 18 4d 85 ff 0f 84 b1 e2 ff ff e8 87 ba 58 ff 49 8d 7f 08 48 89 f8 48 c1 e8 03 42 0f b6 04 30 84 c0 0f 85 e7 1d 00 00 <41> 0f b7 47 08 c1 e0 04 48 8d 04 40 48 89 44 24 10 49 8d 47 28 48 RSP: 0018:ffffc90005026d60 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 0000000000000007 RCX: ffff888023a9bc00 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffffffffffec RBP: ffffc90005027010 R08: ffffffff911bc607 R09: 1ffffffff22378c0 R10: dffffc0000000000 R11: fffffbfff22378c1 R12: 0000000000000001 R13: 1ffff92000a04dd8 R14: dffffc0000000000 R15: ffffffffffffffe4 FS: 00007fa74d2226c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffffffffec CR3: 0000000056230000 CR4: 00000000003506e0 ---------------- Code disassembly (best guess): 0: 8b 7c 24 18 mov 0x18(%rsp),%edi 4: 4d 85 ff test %r15,%r15 7: 0f 84 b1 e2 ff ff je 0xffffe2be d: e8 87 ba 58 ff call 0xff58ba99 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 e7 1d 00 00 jne 0x1e11 * 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: 49 8d 47 28 lea 0x28(%r15),%rax 3f: 48 rex.W