syzbot


UBSAN: shift-out-of-bounds in __bch2_btree_node_hash_insert

Status: upstream: reported C repro on 2025/01/01 11:36
Subsystems: bcachefs
[Documentation on labels]
Reported-by: syzbot+029d1989099aa5ae3e89@syzkaller.appspotmail.com
First crash: 7d12h, last: 7d12h
Cause bisection: introduced by (bisect log) :
commit 46522a75a47ed8db6da54f37c4dcf934e12fe540
Author: Kent Overstreet <kent.overstreet@linux.dev>
Date: Mon Nov 25 05:21:27 2024 +0000

  bcachefs: Bad btree roots are now autofix

Crash: UBSAN: shift-out-of-bounds in __btree_node_pinned (log)
Repro: C syz .config
  
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [bcachefs?] UBSAN: shift-out-of-bounds in __bch2_btree_node_hash_insert 0 (1) 2025/01/01 11:36

Sample crash report:
bcachefs (loop0): running explicit recovery pass check_backpointers_to_extents (16), currently at recovery_pass_empty (0)
bcachefs (loop0): running explicit recovery pass scan_for_btree_nodes (1), currently at recovery_pass_empty (0)
error reading btree root btree=xattrs level=0: btree_node_read_error, fixing
------------[ cut here ]------------
UBSAN: shift-out-of-bounds in fs/bcachefs/btree_cache.c:215:18
shift exponent 251 is too large for 64-bit type 'unsigned long long'
CPU: 0 UID: 0 PID: 5833 Comm: syz-executor472 Not tainted 6.13.0-rc3-next-20241220-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 ubsan_epilogue lib/ubsan.c:231 [inline]
 __ubsan_handle_shift_out_of_bounds+0x3c8/0x420 lib/ubsan.c:468
 __btree_node_pinned fs/bcachefs/btree_cache.c:215 [inline]
 __bch2_btree_node_hash_insert+0x1b1d/0x1b80 fs/bcachefs/btree_cache.c:291
 bch2_btree_node_hash_insert+0x7e/0xc0 fs/bcachefs/btree_cache.c:306
 __bch2_btree_root_read fs/bcachefs/btree_io.c:1783 [inline]
 bch2_btree_root_read+0x5c6/0x7a0 fs/bcachefs/btree_io.c:1811
 read_btree_roots+0x375/0x9e0 fs/bcachefs/recovery.c:582
 bch2_fs_recovery+0x260f/0x3de0 fs/bcachefs/recovery.c:929
 bch2_fs_start+0x37c/0x610 fs/bcachefs/super.c:1032
 bch2_fs_get_tree+0xd8d/0x1740 fs/bcachefs/fs.c:2200
 vfs_get_tree+0x90/0x2b0 fs/super.c:1814
 do_new_mount+0x2be/0xb40 fs/namespace.c:3556
 do_mount fs/namespace.c:3896 [inline]
 __do_sys_mount fs/namespace.c:4107 [inline]
 __se_sys_mount+0x2d6/0x3c0 fs/namespace.c:4084
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f15c224ca4a
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:00007ffd1e726af8 EFLAGS: 00000282 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffd1e726b10 RCX: 00007f15c224ca4a
RDX: 0000000020000180 RSI: 0000000020000540 RDI: 00007ffd1e726b10
RBP: 0000000000000004 R08: 00007ffd1e726b50 R09: 0000000000005964
R10: 0000000000800000 R11: 0000000000000282 R12: 0000000000800000
R13: 00007ffd1e726b50 R14: 0000000000000003 R15: 0000000001000000
 </TASK>
---[ end trace ]---

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/12/28 12:01 linux-next 8155b4ef3466 d3ccff63 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci-upstream-linux-next-kasan-gce-root UBSAN: shift-out-of-bounds in __bch2_btree_node_hash_insert
2024/12/28 11:42 linux-next 8155b4ef3466 d3ccff63 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci-upstream-linux-next-kasan-gce-root UBSAN: shift-out-of-bounds in __bch2_btree_node_hash_insert
2024/12/28 11:29 linux-next 8155b4ef3466 d3ccff63 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root UBSAN: shift-out-of-bounds in __bch2_btree_node_hash_insert
2024/12/28 11:29 linux-next 8155b4ef3466 d3ccff63 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root UBSAN: shift-out-of-bounds in __bch2_btree_node_hash_insert
* Struck through repros no longer work on HEAD.