[syzbot] [bcachefs?] KMSAN: uninit-value in bch2_bucket_alloc_early

syzbot
2024-11-06T13:58:29Z

Hello,

syzbot found the following issue on:

HEAD commit: 11066801dd4b Merge tag 'linux_kselftest-fixes-6.12-rc6' of..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1586755f980000
kernel config: https://syzkaller.appspot.com/x/.config?x=1edd801cefd6ca3e
dashboard link: https://syzkaller.appspot.com/bug?extid=07d7911319bd613ba885
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: i386

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/cc31a4a3feaf/disk-11066801.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/864b7b8a0366/vmlinux-11066801.xz
kernel image: https://storage.googleapis.com/syzbot-assets/1d3aafe2185a/bzImage-11066801.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+07d7911319bd613ba885@syzkaller.appspotmail.com

=====================================================
BUG: KMSAN: uninit-value in bch2_alloc_to_v4 fs/bcachefs/alloc_background.h:235 [inline]
BUG: KMSAN: uninit-value in bch2_bucket_alloc_early+0x11c0/0x2520 fs/bcachefs/alloc_foreground.c:439
bch2_alloc_to_v4 fs/bcachefs/alloc_background.h:235 [inline]
bch2_bucket_alloc_early+0x11c0/0x2520 fs/bcachefs/alloc_foreground.c:439
bch2_bucket_alloc_trans+0x8e6/0x3fb0 fs/bcachefs/alloc_foreground.c:649
bch2_bucket_alloc_set_trans+0x959/0x1650 fs/bcachefs/alloc_foreground.c:808
__open_bucket_add_buckets+0x1dec/0x3070 fs/bcachefs/alloc_foreground.c:1057
open_bucket_add_buckets+0x328/0x530 fs/bcachefs/alloc_foreground.c:1101
bch2_alloc_sectors_start_trans+0x1833/0x32b0
__bch2_btree_node_alloc fs/bcachefs/btree_update_interior.c:343 [inline]
bch2_btree_reserve_get+0x9d6/0x2290 fs/bcachefs/btree_update_interior.c:554
bch2_btree_update_start+0x1af9/0x2d60 fs/bcachefs/btree_update_interior.c:1252
bch2_btree_split_leaf+0x120/0xc00 fs/bcachefs/btree_update_interior.c:1850
bch2_trans_commit_error+0x1c0/0x1d60 fs/bcachefs/btree_trans_commit.c:942
__bch2_trans_commit+0x210f/0xd190 fs/bcachefs/btree_trans_commit.c:1140
bch2_trans_commit fs/bcachefs/btree_update.h:184 [inline]
btree_update_nodes_written fs/bcachefs/btree_update_interior.c:728 [inline]
btree_interior_update_work+0x2080/0x4870 fs/bcachefs/btree_update_interior.c:866
process_one_work kernel/workqueue.c:3229 [inline]
process_scheduled_works+0xae0/0x1c40 kernel/workqueue.c:3310
worker_thread+0xea7/0x14f0 kernel/workqueue.c:3391
kthread+0x3e2/0x540 kernel/kthread.c:389
ret_from_fork+0x6d/0x90 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Uninit was created at:
___kmalloc_large_node+0x22c/0x370 mm/slub.c:4219
__kmalloc_large_node_noprof+0x3f/0x1e0 mm/slub.c:4236
__do_kmalloc_node mm/slub.c:4252 [inline]
__kmalloc_node_noprof+0x9d6/0xf50 mm/slub.c:4270
__kvmalloc_node_noprof+0xc0/0x2d0 mm/util.c:658
btree_node_data_alloc fs/bcachefs/btree_cache.c:125 [inline]
__bch2_btree_node_mem_alloc+0x2c8/0x9d0 fs/bcachefs/btree_cache.c:170
bch2_fs_btree_cache_init+0x4e4/0xb50 fs/bcachefs/btree_cache.c:633
bch2_fs_alloc fs/bcachefs/super.c:916 [inline]
bch2_fs_open+0x4d35/0x5b30 fs/bcachefs/super.c:2064
bch2_fs_get_tree+0x983/0x22d0 fs/bcachefs/fs.c:2157
vfs_get_tree+0xb1/0x5a0 fs/super.c:1814
do_new_mount+0x71f/0x15e0 fs/namespace.c:3507
path_mount+0x742/0x1f10 fs/namespace.c:3834
do_mount fs/namespace.c:3847 [inline]
__do_sys_mount fs/namespace.c:4057 [inline]
__se_sys_mount+0x722/0x810 fs/namespace.c:4034
__ia32_sys_mount+0xe3/0x150 fs/namespace.c:4034
ia32_sys_call+0x2530/0x40d0 arch/x86/include/generated/asm/syscalls_32.h:22
do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
__do_fast_syscall_32+0xb0/0x110 arch/x86/entry/common.c:386
do_fast_syscall_32+0x38/0x80 arch/x86/entry/common.c:411
do_SYSENTER_32+0x1f/0x30 arch/x86/entry/common.c:449
entry_SYSENTER_compat_after_hwframe+0x84/0x8e

CPU: 1 UID: 0 PID: 1882 Comm: kworker/u8:7 Not tainted 6.12.0-rc5-syzkaller-00299-g11066801dd4b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Workqueue: btree_update btree_interior_update_work
=====================================================

---
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@googlegroups.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 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