Message-ID: <68d87d4d.a00a0220.102ee.0020.GAE@google.com>
Date: Sat, 27 Sep 2025 17:11:57 -0700
From: syzbot <syzbot+9f41e4b255897d99d4e9@...kaller.appspotmail.com>
To: linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: Forwarded: Re: [syzbot] [bcachefs?] UBSAN: shift-out-of-bounds in __btree_node_pinned

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Subject: Re: [syzbot] [bcachefs?] UBSAN: shift-out-of-bounds in __btree_node_pinned
Author: xandfury@...il.com

syzbot <syzbot+9f41e4b255897d99d4e9@...kaller.appspotmail.com> writes:

> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:    ad46e8f95e93 Merge tag ’pm-6.12-rc1-2’ of git://git.kernel..
> git tree:       upstream
> console output: <https://syzkaller.appspot.com/x/log.txt?x=13b3d507980000>
> kernel config:  <https://syzkaller.appspot.com/x/.config?x=62086b2fd100a029>
> dashboard link: <https://syzkaller.appspot.com/bug?extid=9f41e4b255897d99d4e9>
> compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> syz repro:      <https://syzkaller.appspot.com/x/repro.syz?x=11b69e80580000>
> C reproducer:   <https://syzkaller.appspot.com/x/repro.c?x=1567c6a9980000>
>
> Downloadable assets:
> disk image (non-bootable): <https://storage.googleapis.com/syzbot-assets/7feb34a89c2a/non_bootable_disk-ad46e8f9.raw.xz>
> vmlinux: <https://storage.googleapis.com/syzbot-assets/72b7539cbeb1/vmlinux-ad46e8f9.xz>
> kernel image: <https://storage.googleapis.com/syzbot-assets/73c9b9cebaf4/bzImage-ad46e8f9.xz>
> mounted in repro: <https://storage.googleapis.com/syzbot-assets/54e2032c8f9d/mount_0.gz>
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+9f41e4b255897d99d4e9@...kaller.appspotmail.com
>
> ————[ cut here ]————
> UBSAN: shift-out-of-bounds in fs/bcachefs/btree_cache.c:198:18
> shift exponent 227 is too large for 64-bit type ’unsigned long long’
> CPU: 0 UID: 0 PID: 5109 Comm: read_btree_node Not tainted 6.11.0-syzkaller-11728-gad46e8f95e93 #0
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
> 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+0x80b/0x850 fs/bcachefs/btree_cache.c:198
>  __bch2_btree_node_hash_insert+0xcfd/0x13e0 fs/bcachefs/btree_cache.c:270
>  bch2_btree_node_hash_insert fs/bcachefs/btree_cache.c:287 [inline]
>  bch2_btree_node_fill+0x94e/0x1200 fs/bcachefs/btree_cache.c:932
>  bch2_btree_node_get_noiter+0x9d5/0xf70 fs/bcachefs/btree_cache.c:1238
>  found_btree_node_is_readable fs/bcachefs/btree_node_scan.c:85 [inline]
>  try_read_btree_node fs/bcachefs/btree_node_scan.c:190 [inline]
>  read_btree_nodes_worker+0x122c/0x20b0 fs/bcachefs/btree_node_scan.c:239
>  kthread+0x2f0/0x390 kernel/kthread.c:389
>  ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
>  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
>  </TASK>
> —[ end trace ]—
> Kernel panic - not syncing: UBSAN: panic_on_warn set …
> CPU: 0 UID: 0 PID: 5109 Comm: read_btree_node Not tainted 6.11.0-syzkaller-11728-gad46e8f95e93 #0
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
> Call Trace:
>  <TASK>
>  __dump_stack lib/dump_stack.c:94 [inline]
>  dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
>  panic+0x349/0x880 kernel/panic.c:354
>  check_panic_on_warn+0x86/0xb0 kernel/panic.c:243
>  ubsan_epilogue lib/ubsan.c:236 [inline]
>  __ubsan_handle_shift_out_of_bounds+0x3e7/0x420 lib/ubsan.c:468
>  __btree_node_pinned+0x80b/0x850 fs/bcachefs/btree_cache.c:198
>  __bch2_btree_node_hash_insert+0xcfd/0x13e0 fs/bcachefs/btree_cache.c:270
>  bch2_btree_node_hash_insert fs/bcachefs/btree_cache.c:287 [inline]
>  bch2_btree_node_fill+0x94e/0x1200 fs/bcachefs/btree_cache.c:932
>  bch2_btree_node_get_noiter+0x9d5/0xf70 fs/bcachefs/btree_cache.c:1238
>  found_btree_node_is_readable fs/bcachefs/btree_node_scan.c:85 [inline]
>  try_read_btree_node fs/bcachefs/btree_node_scan.c:190 [inline]
>  read_btree_nodes_worker+0x122c/0x20b0 fs/bcachefs/btree_node_scan.c:239
>  kthread+0x2f0/0x390 kernel/kthread.c:389
>  ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
>  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
>  </TASK>
> Kernel Offset: disabled
> Rebooting in 86400 seconds..
>
>
> —
> This report is generated by a bot. It may contain errors.
> See <https://goo.gl/tpsmEJ> for more information about syzbot.
> syzbot engineers can be reached at syzkaller@...glegroups.com.
>
> syzbot will keep track of this issue. See:
> <https://goo.gl/tpsmEJ#status> for how to communicate with syzbot.
>
> If the report is already addressed, let syzbot know by replying with:
> #syz fix: exact-commit-title
>
> If you want syzbot to run the reproducer, reply with:
> #syz test: git://repo/address.git branch-or-commit-hash
> If you attach or paste a git patch, syzbot will apply it before testing.
>
> If you want to overwrite report’s subsystems, reply with:
> #syz set subsystems: new-subsystem
> (See the list of subsystem names on the web dashboard)
>
> If the report is a duplicate of another one, reply with:
> #syz dup: exact-subject-of-another-report
>
> If you want to undo deduplication, reply with:
> #syz undup

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master

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