linux-kernel - Re: [syzbot] [bcachefs?] KMSAN: uninit-value in bch2_bkey_cmp_packed

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Message-ID: <67b1c23d.050a0220.54b41.0007.GAE@google.com>
Date: Sun, 16 Feb 2025 02:47:25 -0800
From: syzbot <syzbot+65b594f491e4023728b0@...kaller.appspotmail.com>
To: kent.overstreet@...ux.dev, linux-bcachefs@...r.kernel.org, 
	linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [bcachefs?] KMSAN: uninit-value in bch2_bkey_cmp_packed_inlined
 (2)

syzbot has found a reproducer for the following issue on:

HEAD commit:    496659003dac Merge tag 'i2c-for-6.14-rc3' of git://git.ker..
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=12c2d5a4580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=264db44f1897cdc3
dashboard link: https://syzkaller.appspot.com/bug?extid=65b594f491e4023728b0
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=161d2bf8580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=172a97df980000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/96211a6dd5b7/disk-49665900.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/28af00be6abb/vmlinux-49665900.xz
kernel image: https://storage.googleapis.com/syzbot-assets/250398195b35/bzImage-49665900.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/25c6d0c4b587/mount_2.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+65b594f491e4023728b0@...kaller.appspotmail.com

=====================================================
BUG: KMSAN: uninit-value in bch2_bkey_cmp_packed_inlined+0x8d0/0xd50 fs/bcachefs/bkey_cmp.h:115
 bch2_bkey_cmp_packed_inlined+0x8d0/0xd50 fs/bcachefs/bkey_cmp.h:115
 bch2_sort_keys_keep_unwritten_whiteouts+0xebd/0x1840 fs/bcachefs/bkey_sort.c:184
 __bch2_btree_node_write+0x3b3f/0x6870 fs/bcachefs/btree_io.c:2140
 bch2_btree_node_write_trans+0xd7/0x890 fs/bcachefs/btree_io.c:2357
 btree_node_write_if_need fs/bcachefs/btree_io.h:153 [inline]
 btree_update_nodes_written fs/bcachefs/btree_update_interior.c:816 [inline]
 btree_interior_update_work+0x3c02/0x48c0 fs/bcachefs/btree_update_interior.c:844
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0xc1a/0x1e80 kernel/workqueue.c:3317
 worker_thread+0xea7/0x14f0 kernel/workqueue.c:3398
 kthread+0x6b9/0xef0 kernel/kthread.c:464
 ret_from_fork+0x6d/0x90 arch/x86/kernel/process.c:148
 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:4249
 __kmalloc_large_node_noprof+0x3f/0x1e0 mm/slub.c:4266
 __do_kmalloc_node mm/slub.c:4282 [inline]
 __kmalloc_node_noprof+0xc96/0x1250 mm/slub.c:4300
 __kvmalloc_node_noprof+0xc0/0x2d0 mm/util.c:662
 btree_node_data_alloc fs/bcachefs/btree_cache.c:156 [inline]
 __bch2_btree_node_mem_alloc+0x2be/0xa80 fs/bcachefs/btree_cache.c:201
 bch2_fs_btree_cache_init+0x4f0/0xb60 fs/bcachefs/btree_cache.c:655
 bch2_fs_alloc fs/bcachefs/super.c:919 [inline]
 bch2_fs_open+0x4d84/0x5ba0 fs/bcachefs/super.c:2064
 bch2_fs_get_tree+0x98a/0x24e0 fs/bcachefs/fs.c:2190
 vfs_get_tree+0xb1/0x5a0 fs/super.c:1814
 do_new_mount+0x71f/0x15e0 fs/namespace.c:3560
 path_mount+0x742/0x1f10 fs/namespace.c:3887
 do_mount fs/namespace.c:3900 [inline]
 __do_sys_mount fs/namespace.c:4111 [inline]
 __se_sys_mount+0x71f/0x800 fs/namespace.c:4088
 __x64_sys_mount+0xe4/0x150 fs/namespace.c:4088
 x64_sys_call+0x39bf/0x3c30 arch/x86/include/generated/asm/syscalls_64.h:166
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

CPU: 1 UID: 0 PID: 3010 Comm: kworker/u8:7 Not tainted 6.14.0-rc2-syzkaller-00281-g496659003dac #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
Workqueue: btree_update btree_interior_update_work
=====================================================


---
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.