[syzbot] [hfs?] KMSAN: uninit-value in hfs_find_1st_rec_by_cnid

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: a4145ce1e7bc Merge tag 'bcachefs-2024-03-19' of https://ev..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=1312764e180000
kernel config: https://syzkaller.appspot.com/x/.config?x=5c1d7ee7e74661a8
dashboard link: https://syzkaller.appspot.com/bug?extid=65f53dd6a0f7ad64c0cb
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=1737d879180000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15f5c2a5180000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/ce90c7e9c4b9/disk-a4145ce1.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/fc2e82754c55/vmlinux-a4145ce1.xz
kernel image: https://storage.googleapis.com/syzbot-assets/dfc8b656ea07/bzImage-a4145ce1.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/acef21cf3ab0/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+65f53d...@syzkaller.appspotmail.com

loop0: detected capacity change from 0 to 1024
=====================================================
BUG: KMSAN: uninit-value in hfs_find_1st_rec_by_cnid+0x27a/0x3f0 fs/hfsplus/bfind.c:78
hfs_find_1st_rec_by_cnid+0x27a/0x3f0 fs/hfsplus/bfind.c:78
__hfsplus_brec_find+0x26f/0x7b0 fs/hfsplus/bfind.c:135
hfsplus_brec_find+0x445/0x970 fs/hfsplus/bfind.c:195
hfsplus_find_attr+0x30c/0x390
hfsplus_listxattr+0x586/0x1a60 fs/hfsplus/xattr.c:708
vfs_listxattr fs/xattr.c:493 [inline]
listxattr+0x1f3/0x6b0 fs/xattr.c:840
path_listxattr fs/xattr.c:864 [inline]
__do_sys_listxattr fs/xattr.c:876 [inline]
__se_sys_listxattr fs/xattr.c:873 [inline]
__x64_sys_listxattr+0x16b/0x2f0 fs/xattr.c:873
do_syscall_64+0xd5/0x1f0
entry_SYSCALL_64_after_hwframe+0x6d/0x75

Uninit was created at:
slab_post_alloc_hook mm/slub.c:3804 [inline]
slab_alloc_node mm/slub.c:3845 [inline]
__do_kmalloc_node mm/slub.c:3965 [inline]
__kmalloc+0x6e4/0x1000 mm/slub.c:3979
kmalloc include/linux/slab.h:632 [inline]
hfsplus_find_init+0x91/0x250 fs/hfsplus/bfind.c:21
hfsplus_listxattr+0x44a/0x1a60 fs/hfsplus/xattr.c:695
vfs_listxattr fs/xattr.c:493 [inline]
listxattr+0x1f3/0x6b0 fs/xattr.c:840
path_listxattr fs/xattr.c:864 [inline]
__do_sys_listxattr fs/xattr.c:876 [inline]
__se_sys_listxattr fs/xattr.c:873 [inline]
__x64_sys_listxattr+0x16b/0x2f0 fs/xattr.c:873
do_syscall_64+0xd5/0x1f0
entry_SYSCALL_64_after_hwframe+0x6d/0x75

CPU: 0 PID: 5013 Comm: syz-executor378 Not tainted 6.8.0-syzkaller-11743-ga4145ce1e7bc #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024
=====================================================


---
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 syzk...@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 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

[Edward Adam Davis]

please test uninit-value in hfs_find_1st_rec_by_cnid

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
diff --git a/fs/hfsplus/bfind.c b/fs/hfsplus/bfind.c
index ca2ba8c9f82e..b939dc879dac 100644
--- a/fs/hfsplus/bfind.c
+++ b/fs/hfsplus/bfind.c
@@ -18,7 +18,7 @@ int hfs_find_init(struct hfs_btree *tree, struct hfs_find_data *fd)

fd->tree = tree;
fd->bnode = NULL;
- ptr = kmalloc(tree->max_key_len * 2 + 4, GFP_KERNEL);
+ ptr = kzalloc(tree->max_key_len * 2 + 4, GFP_KERNEL);
if (!ptr)
return -ENOMEM;
fd->search_key = ptr;

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+65f53d...@syzkaller.appspotmail.com

Tested on:

commit: 23956900 Merge tag 'v6.9-rc-smb3-server-fixes' of git:..
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=161b324e180000

kernel config: https://syzkaller.appspot.com/x/.config?x=5c1d7ee7e74661a8
dashboard link: https://syzkaller.appspot.com/bug?extid=65f53dd6a0f7ad64c0cb
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

patch: https://syzkaller.appspot.com/x/patch.diff?x=11206479180000

Note: testing is done by a robot and is best-effort only.

[Edward Adam Davis]

[syzbot reported]

[Fix]
Let's clear all search_key fields at alloc time.

Reported-and-tested-by: syzbot+65f53d...@syzkaller.appspotmail.com
Signed-off-by: Edward Adam Davis <ead...@qq.com>
---
fs/hfsplus/bfind.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/hfsplus/bfind.c b/fs/hfsplus/bfind.c
index ca2ba8c9f82e..b939dc879dac 100644
--- a/fs/hfsplus/bfind.c
+++ b/fs/hfsplus/bfind.c
@@ -18,7 +18,7 @@ int hfs_find_init(struct hfs_btree *tree, struct hfs_find_data *fd)

fd->tree = tree;
fd->bnode = NULL;
- ptr = kmalloc(tree->max_key_len * 2 + 4, GFP_KERNEL);
+ ptr = kzalloc(tree->max_key_len * 2 + 4, GFP_KERNEL);
if (!ptr)
return -ENOMEM;
fd->search_key = ptr;

--
2.43.0