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UBSAN: array-index-out-of-bounds in bch2_accounting_validate

Status: upstream: reported C repro on 2025/08/04 07:18
Subsystems: bcachefs
[Documentation on labels]
Reported-by: syzbot+cd063f869beedf5b9cd7@syzkaller.appspotmail.com
Fix commit: bcachefs: Ignore accounting key type larger than BCH_DISK_ACCOUNTING_TYPE_NR
Patched on: [ci-upstream-linux-next-kasan-gce-root ci-upstream-rust-kasan-gce], 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-net-kasan-gce ci-upstream-net-this-kasan-gce ci2-upstream-fs ci2-upstream-kcsan-gce ci2-upstream-usb]
First crash: 46d, last: 14h58m
Cause bisection: introduced by (bisect log) :
commit 557f8c582a9ba8abe6aa0fd734b6f342af106b26
Author: Kees Cook <keescook@chromium.org>
Date: Thu Jan 18 23:06:05 2024 +0000

  ubsan: Reintroduce signed overflow sanitizer

Crash: UBSAN: signed-integer-overflow in mean_and_variance_weighted_update (log)
Repro: C syz .config
  
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [bcachefs?] UBSAN: array-index-out-of-bounds in bch2_accounting_validate 2 (7) 2025/08/04 22:56
▶ ▼ Last patch testing requests (1)
Created Duration User Patch Repo Result
2025/08/04 12:21 1h52m mmpgouride@gmail.com patch upstream error

Sample crash report:
bcachefs (loop0): error reading btree root btree=subvolumes level=0: btree_node_read_error, fixing
bcachefs (loop0): invalid bkey in btree_node btree=snapshot_trees level=0: u64s 6 type snapshot_tree POS_MIN len 0 ver 0: subvol 1 root snapshot 4294967295
  bad pos, deleting
bcachefs (loop0): error reading btree root btree=snapshot_trees level=0: btree_node_read_error, fixing
------------[ cut here ]------------
UBSAN: array-index-out-of-bounds in fs/bcachefs/disk_accounting.c:238:2
index 175 is out of range for type 'const unsigned int[9]'
CPU: 0 UID: 0 PID: 5849 Comm: syz-executor427 Tainted: G        W           6.16.0-syzkaller-11322-g352af6a011d5 #0 PREEMPT_{RT,(full)} 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 ubsan_epilogue+0xa/0x40 lib/ubsan.c:233
 __ubsan_handle_out_of_bounds+0xe9/0xf0 lib/ubsan.c:455
 bch2_accounting_validate+0x112f/0x1400 fs/bcachefs/disk_accounting.c:238
 bch2_bkey_val_validate+0x202/0x3e0 fs/bcachefs/bkey_methods.c:143
 btree_node_bkey_val_validate fs/bcachefs/btree_io.c:880 [inline]
 bch2_btree_node_read_done+0x4051/0x5550 fs/bcachefs/btree_io.c:1303
 btree_node_read_work+0x40e/0xe60 fs/bcachefs/btree_io.c:1440
 bch2_btree_node_read+0x887/0x2a00 fs/bcachefs/btree_io.c:-1
 __bch2_btree_root_read fs/bcachefs/btree_io.c:1906 [inline]
 bch2_btree_root_read+0x5f0/0x760 fs/bcachefs/btree_io.c:1928
 read_btree_roots+0x2c6/0x840 fs/bcachefs/recovery.c:615
 bch2_fs_recovery+0x261f/0x3a50 fs/bcachefs/recovery.c:1006
 bch2_fs_start+0xaaf/0xda0 fs/bcachefs/super.c:1213
 bch2_fs_get_tree+0xb39/0x1520 fs/bcachefs/fs.c:2488
 vfs_get_tree+0x92/0x2b0 fs/super.c:1815
 do_new_mount+0x2a2/0x9e0 fs/namespace.c:3805
 do_mount fs/namespace.c:4133 [inline]
 __do_sys_mount fs/namespace.c:4344 [inline]
 __se_sys_mount+0x317/0x410 fs/namespace.c:4321
 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: 0033:0x7f5016bf5eaa
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 5e 04 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 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:00007ffd552f5c58 EFLAGS: 00000282 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffd552f5c70 RCX: 00007f5016bf5eaa
RDX: 0000200000001000 RSI: 0000200000000000 RDI: 00007ffd552f5c70
RBP: 0000200000000000 R08: 00007ffd552f5cb0 R09: 000000000000492c
R10: 0000000000000000 R11: 0000000000000282 R12: 0000200000001000
R13: 00007ffd552f5cb0 R14: 0000000000000003 R15: 0000000000000000
 </TASK>
---[ end trace ]---

Crashes (19):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/08/04 07:16 upstream 352af6a011d5 7368264b .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-upstream-fs UBSAN: array-index-out-of-bounds in bch2_accounting_validate
2025/08/04 03:11 upstream 352af6a011d5 7368264b .config console log report syz / log C [disk image (non-bootable)] [vmlinux] [kernel image] [mounted in repro] ci-snapshot-upstream-root UBSAN: array-index-out-of-bounds in bch2_accounting_validate
2025/08/04 02:59 upstream 352af6a011d5 7368264b .config console log report syz / log C [disk image (non-bootable)] [vmlinux] [kernel image] [mounted in repro] ci-snapshot-upstream-root UBSAN: array-index-out-of-bounds in bch2_accounting_validate
2025/08/17 06:42 upstream 90d970cade8e 1804e95e .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs UBSAN: array-index-out-of-bounds in bch2_accounting_validate
2025/09/18 21:30 upstream 8b789f2b7602 e2beed91 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root UBSAN: array-index-out-of-bounds in bch2_accounting_validate
2025/09/15 04:33 upstream 79e8447ec662 e2beed91 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root UBSAN: array-index-out-of-bounds in bch2_accounting_validate
2025/09/14 04:26 upstream 5cd64d4f9268 e2beed91 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root UBSAN: array-index-out-of-bounds in bch2_accounting_validate
2025/09/12 21:18 upstream 22f20375f5b7 e2beed91 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root UBSAN: array-index-out-of-bounds in bch2_accounting_validate
2025/09/12 18:22 upstream 320475fbd590 e2beed91 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root UBSAN: array-index-out-of-bounds in bch2_accounting_validate
2025/09/09 11:43 upstream f777d1112ee5 d291dd2d .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root UBSAN: array-index-out-of-bounds in bch2_accounting_validate
2025/08/30 21:54 upstream 11e7861d680c 807a3b61 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root UBSAN: array-index-out-of-bounds in bch2_accounting_validate
2025/08/30 08:50 upstream fb679c832b64 807a3b61 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root UBSAN: array-index-out-of-bounds in bch2_accounting_validate
2025/08/21 11:11 upstream 41cd3fd15263 0b9605c8 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root UBSAN: array-index-out-of-bounds in bch2_accounting_validate
2025/08/18 16:08 upstream c17b750b3ad9 dcc075fb .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root UBSAN: array-index-out-of-bounds in bch2_accounting_validate
2025/08/16 22:35 upstream 90d970cade8e dcc075fb .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root UBSAN: array-index-out-of-bounds in bch2_accounting_validate
2025/08/14 08:30 upstream dfc0f6373094 22ec1469 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root UBSAN: array-index-out-of-bounds in bch2_accounting_validate
2025/08/11 01:34 upstream 2b38afce25c4 32a0e5ed .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root UBSAN: array-index-out-of-bounds in bch2_accounting_validate
2025/08/09 19:34 upstream c30a13538d9f 32a0e5ed .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root UBSAN: array-index-out-of-bounds in bch2_accounting_validate
2025/08/04 02:45 upstream 352af6a011d5 7368264b .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root UBSAN: array-index-out-of-bounds in bch2_accounting_validate
* Struck through repros no longer work on HEAD.