linux-kernel - Re: [syzbot] [bcachefs?] KMSAN: uninit-value in bch2_dev_freespace

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Message-ID: <676159c5.050a0220.37aaf.0166.GAE@google.com>
Date: Tue, 17 Dec 2024 03:00:21 -0800
From: syzbot <syzbot+aa2232cb0e5de0c0b56f@...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_dev_freespace_init

syzbot has found a reproducer for the following issue on:

HEAD commit:    f44d154d6e3d Merge tag 'soc-fixes-6.13' of git://git.kerne..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13c0a7e8580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=caeefc00e8b4dc9f
dashboard link: https://syzkaller.appspot.com/bug?extid=aa2232cb0e5de0c0b56f
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=10dc74f8580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/009edf262d35/disk-f44d154d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/9929be9055fe/vmlinux-f44d154d.xz
kernel image: https://storage.googleapis.com/syzbot-assets/24e56358f05d/bzImage-f44d154d.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/18b4c753db11/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+aa2232cb0e5de0c0b56f@...kaller.appspotmail.com

bcachefs (loop1): going read-write
bcachefs (loop1): marking superblocks
bcachefs (loop1): initializing freespace
=====================================================
BUG: KMSAN: uninit-value in bch2_alloc_to_v4 fs/bcachefs/alloc_background.h:235 [inline]
BUG: KMSAN: uninit-value in bch2_dev_freespace_init+0x1044/0x1eb0 fs/bcachefs/alloc_background.c:2232
 bch2_alloc_to_v4 fs/bcachefs/alloc_background.h:235 [inline]
 bch2_dev_freespace_init+0x1044/0x1eb0 fs/bcachefs/alloc_background.c:2232
 bch2_fs_freespace_init+0x599/0xb30 fs/bcachefs/alloc_background.c:2304
 bch2_fs_initialize+0x2140/0x35d0 fs/bcachefs/recovery.c:1082
 bch2_fs_start+0x77d/0xbd0 fs/bcachefs/super.c:1038
 bch2_fs_get_tree+0x13ea/0x22d0 fs/bcachefs/fs.c:2170
 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
 __x64_sys_mount+0xe4/0x150 fs/namespace.c:4034
 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

Uninit was created at:
 ___kmalloc_large_node+0x22c/0x370 mm/slub.c:4253
 __kmalloc_large_node_noprof+0x3f/0x1e0 mm/slub.c:4270
 __do_kmalloc_node mm/slub.c:4286 [inline]
 __kmalloc_node_noprof+0xc96/0x1250 mm/slub.c:4304
 __kvmalloc_node_noprof+0xc0/0x2d0 mm/util.c:650
 btree_node_data_alloc fs/bcachefs/btree_cache.c:153 [inline]
 __bch2_btree_node_mem_alloc+0x2be/0xa80 fs/bcachefs/btree_cache.c:198
 bch2_fs_btree_cache_init+0x4e4/0xb50 fs/bcachefs/btree_cache.c:653
 bch2_fs_alloc fs/bcachefs/super.c:917 [inline]
 bch2_fs_open+0x4d3a/0x5b40 fs/bcachefs/super.c:2065
 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
 __x64_sys_mount+0xe4/0x150 fs/namespace.c:4034
 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: 6157 Comm: syz.1.21 Not tainted 6.13.0-rc3-syzkaller-00017-gf44d154d6e3d #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/25/2024
=====================================================


---
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.