syzbot


kernel BUG in bch2_fill_extent (2)

Status: upstream: reported on 2025/07/15 07:40
Subsystems: bcachefs
[Documentation on labels]
Reported-by: syzbot+397f6fe952a0defb9424@syzkaller.appspotmail.com
Fix commit: bcachefs: Fix unhandled key type in fiemap_fill_extent
Patched on: [], missing on: [ci-qemu-gce-upstream-auto ci-qemu-native-arm64-kvm ci-qemu-upstream ci-qemu-upstream-386 ci-qemu2-arm32 ci-qemu2-arm64 ci-qemu2-arm64-compat ci-qemu2-arm64-mte ci-qemu2-riscv64 ci-snapshot-upstream-root ci-upstream-bpf-kasan-gce ci-upstream-bpf-next-kasan-gce ci-upstream-gce-arm64 ci-upstream-gce-leak ci-upstream-kasan-badwrites-root ci-upstream-kasan-gce ci-upstream-kasan-gce-386 ci-upstream-kasan-gce-root ci-upstream-kasan-gce-selinux-root ci-upstream-kasan-gce-smack-root ci-upstream-kmsan-gce-386-root ci-upstream-kmsan-gce-root ci-upstream-linux-next-kasan-gce-root ci-upstream-net-kasan-gce ci-upstream-net-this-kasan-gce ci-upstream-rust-kasan-gce ci2-upstream-fs ci2-upstream-kcsan-gce ci2-upstream-usb]
First crash: 14d, last: 3d02h
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [bcachefs?] kernel BUG in bch2_fill_extent (2) 1 (2) 2025/07/19 18:38
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream kernel BUG in bch2_fill_extent bcachefs -1 8 67d 87d 29/29 fixed on 2025/07/10 09:09

Sample crash report:
bcachefs (loop0): accounting_read... done
bcachefs (loop0): alloc_read... done
bcachefs (loop0): snapshots_read... done
bcachefs (loop0): check_allocations...
bcachefs (loop0): pointer to nonexistent device 237
bcachefs (loop0): pointer to missing device 237
  while marking u64s 7 type extent 536870913:24:U32_MAX len 24 ver 0: durability: 0 crc: c_size 8 size 24 offset 0 nonce 0 csum none 0:0  compress lz4 ptr: 237:893353206280 gen 0, fixing
bcachefs (loop0): pointer to nonexistent device 237
 done
bcachefs (loop0): going read-write
bcachefs (loop0): journal_replay... done
bcachefs (loop0): check_alloc_info... done
bcachefs (loop0): check_lrus... done
bcachefs (loop0): check_btree_backpointers... done
bcachefs (loop0): check_backpointers_to_extents... done
bcachefs (loop0): check_extents_to_backpointers...
bcachefs (loop0): scanning for missing backpointers in 9/128 buckets
 done
bcachefs (loop0): check_alloc_to_lru_refs... done
bcachefs (loop0): bucket_gens_init... done
bcachefs (loop0): check_snapshot_trees... done
bcachefs (loop0): check_snapshots...
bcachefs (loop0): snapshot points to missing/incorrect tree:
  u64s 8 type snapshot 0:4294967295:0 len 0 ver 0: subvol parent          0 children          0          0 subvol 1 tree 0, fixing
 done
bcachefs (loop0): check_subvols... done
bcachefs (loop0): check_subvol_children... done
bcachefs (loop0): delete_dead_snapshots... done
bcachefs (loop0): check_inodes... done
bcachefs (loop0): check_extents... done
bcachefs (loop0): check_indirect_extents... done
bcachefs (loop0): check_dirents... done
bcachefs (loop0): check_xattrs... done
bcachefs (loop0): check_root... done
bcachefs (loop0): check_unreachable_inodes... done
bcachefs (loop0): check_subvolume_structure... done
bcachefs (loop0): check_directory_structure... done
bcachefs (loop0): check_nlinks...
bcachefs (loop0): inode 536870914 type reg has wrong i_nlink (2780562353, should be 1), fixing
 done
bcachefs (loop0): check_rebalance_work... done
bcachefs (loop0): resume_logged_ops... done
bcachefs (loop0): delete_dead_inodes... done
bcachefs (loop0): set_fs_needs_rebalance... done
bcachefs (loop0): done starting filesystem
bcachefs (loop0): /file1 offset 0: key_type_error
  u64s 5 type error 536870913:24:U32_MAX len 24 ver 0
bcachefs (loop0): /file1 offset 0: key_type_error
  u64s 5 type error 536870913:24:U32_MAX len 24 ver 0
------------[ cut here ]------------
kernel BUG at fs/bcachefs/fs.c:1323!
Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 5343 Comm: syz.0.0 Not tainted 6.16.0-rc7-syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:bch2_fill_extent+0x96e/0x970 fs/bcachefs/fs.c:1323
Code: 0f 0b e8 25 62 86 fd 90 0f 0b e8 1d 62 86 fd e9 f7 fe ff ff e8 13 62 86 fd 90 0f 0b e8 0b 62 86 fd 90 0f 0b e8 03 62 86 fd 90 <0f> 0b 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 55 41 57 41
RSP: 0018:ffffc9000d64f520 EFLAGS: 00010287
RAX: ffffffff8439cefd RBX: 0000000000000018 RCX: 0000000000100000
RDX: ffffc9000e1b2000 RSI: 000000000000191a RDI: 000000000000191b
RBP: 0000000000000001 R08: ffff88801f77c880 R09: 0000000000000004
R10: 0000000000000012 R11: 0000000000000002 R12: 0000000000000000
R13: ffffc9000d64f9a8 R14: 0000000000000002 R15: 0000000000000002
FS:  00007fdfc63d86c0(0000) GS:ffff88808d218000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f544f58b000 CR3: 0000000042baa000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 bch2_fiemap+0x2871/0x2a90 fs/bcachefs/fs.c:1538
 ioctl_fiemap fs/ioctl.c:220 [inline]
 do_vfs_ioctl+0x16d3/0x1990 fs/ioctl.c:841
 __do_sys_ioctl fs/ioctl.c:905 [inline]
 __se_sys_ioctl+0x82/0x170 fs/ioctl.c:893
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fdfc558e9a9
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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fdfc63d8038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fdfc57b5fa0 RCX: 00007fdfc558e9a9
RDX: 00002000000001c0 RSI: 00000000c020660b RDI: 0000000000000009
RBP: 00007fdfc5610d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fdfc57b5fa0 R15: 00007ffd44166238
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:bch2_fill_extent+0x96e/0x970 fs/bcachefs/fs.c:1323
Code: 0f 0b e8 25 62 86 fd 90 0f 0b e8 1d 62 86 fd e9 f7 fe ff ff e8 13 62 86 fd 90 0f 0b e8 0b 62 86 fd 90 0f 0b e8 03 62 86 fd 90 <0f> 0b 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 55 41 57 41
RSP: 0018:ffffc9000d64f520 EFLAGS: 00010287
RAX: ffffffff8439cefd RBX: 0000000000000018 RCX: 0000000000100000
RDX: ffffc9000e1b2000 RSI: 000000000000191a RDI: 000000000000191b
RBP: 0000000000000001 R08: ffff88801f77c880 R09: 0000000000000004
R10: 0000000000000012 R11: 0000000000000002 R12: 0000000000000000
R13: ffffc9000d64f9a8 R14: 0000000000000002 R15: 0000000000000002
FS:  00007fdfc63d86c0(0000) GS:ffff88808d218000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fdfc63b5fb8 CR3: 0000000042baa000 CR4: 0000000000352ef0

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/23 00:10 upstream 89be9a83ccf1 af30dea9 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root kernel BUG in bch2_fill_extent
2025/07/11 07:34 upstream bc9ff192a6c9 3cda49cf .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root kernel BUG in bch2_fill_extent
* Struck through repros no longer work on HEAD.