hfsplus: fix held lock freed on hfsplus_fill_super()

In the Linux kernel, the following vulnerability has been resolved:

hfsplus: fix held lock freed on hfsplus_fill_super()

hfsplus_fill_super() calls hfs_find_init() to initialize a search

structure, which acquires tree->tree_lock. If the subsequent call to

hfsplus_cat_build_key() fails, the function jumps to the out_put_root

error label without releasing the lock. The later cleanup path then

frees the tree data structure with the lock still held, triggering a

held lock freed warning.

Fix this by adding the missing hfs_find_exit(&fd) call before jumping

to the out_put_root error label. This ensures that tree->tree_lock is

properly released on the error path.

The bug was originally detected on v6.13-rc1 using an experimental

static analysis tool we are developing, and we have verified that the

issue persists in the latest mainline kernel. The tool is specifically

designed to detect memory management issues. It is currently under active

development and not yet publicly available.

We confirmed the bug by runtime testing under QEMU with x86_64 defconfig,

lockdep enabled, and CONFIG_HFSPLUS_FS=y. To trigger the error path, we

used GDB to dynamically shrink the max_unistr_len parameter to 1 before

hfsplus_asc2uni() is called. This forces hfsplus_asc2uni() to naturally

return -ENAMETOOLONG, which propagates to hfsplus_cat_build_key() and

exercises the faulty error path. The following warning was observed

during mount:

=========================

WARNING: held lock freed!

7.0.0-rc3-00016-gb4f0dd314b39 #4 Not tainted

-------------------------

mount/174 is freeing memory ffff888103f92000-ffff888103f92fff, with a lock still held there!

ffff888103f920b0 (&tree->tree_lock){+.+.}-{4:4}, at: hfsplus_find_init+0x154/0x1e0

2 locks held by mount/174:

#0: ffff888103f960e0 (&type->s_umount_key#42/1){+.+.}-{4:4}, at: alloc_super.constprop.0+0x167/0xa40

#1: ffff888103f920b0 (&tree->tree_lock){+.+.}-{4:4}, at: hfsplus_find_init+0x154/0x1e0

stack backtrace:

CPU: 2 UID: 0 PID: 174 Comm: mount Not tainted 7.0.0-rc3-00016-gb4f0dd314b39 #4 PREEMPT(lazy)

Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.15.0-1 04/01/2014

Call Trace:

<TASK>

dump_stack_lvl+0x82/0xd0

debug_check_no_locks_freed+0x13a/0x180

kfree+0x16b/0x510

? hfsplus_fill_super+0xcb4/0x18a0

hfsplus_fill_super+0xcb4/0x18a0

? __pfx_hfsplus_fill_super+0x10/0x10

? srso_return_thunk+0x5/0x5f

? bdev_open+0x65f/0xc30

? srso_return_thunk+0x5/0x5f

? pointer+0x4ce/0xbf0

? trace_contention_end+0x11c/0x150

? __pfx_pointer+0x10/0x10

? srso_return_thunk+0x5/0x5f

? bdev_open+0x79b/0xc30

? srso_return_thunk+0x5/0x5f

? srso_return_thunk+0x5/0x5f

? vsnprintf+0x6da/0x1270

? srso_return_thunk+0x5/0x5f

? __mutex_unlock_slowpath+0x157/0x740

? __pfx_vsnprintf+0x10/0x10

? srso_return_thunk+0x5/0x5f

? srso_return_thunk+0x5/0x5f

? mark_held_locks+0x49/0x80

? srso_return_thunk+0x5/0x5f

? srso_return_thunk+0x5/0x5f

? irqentry_exit+0x17b/0x5e0

? trace_irq_disable.constprop.0+0x116/0x150

? __pfx_hfsplus_fill_super+0x10/0x10

? __pfx_hfsplus_fill_super+0x10/0x10

get_tree_bdev_flags+0x302/0x580

? __pfx_get_tree_bdev_flags+0x10/0x10

? vfs_parse_fs_qstr+0x129/0x1a0

? __pfx_vfs_parse_fs_qstr+0x3/0x10

vfs_get_tree+0x89/0x320

fc_mount+0x10/0x1d0

path_mount+0x5c5/0x21c0

? __pfx_path_mount+0x10/0x10

? trace_irq_enable.constprop.0+0x116/0x150

? trace_irq_enable.constprop.0+0x116/0x150

? srso_return_thunk+0x5/0x5f

? srso_return_thunk+0x5/0x5f

? kmem_cache_free+0x307/0x540

? user_path_at+0x51/0x60

? __x64_sys_mount+0x212/0x280

? srso_return_thunk+0x5/0x5f

__x64_sys_mount+0x212/0x280

? __pfx___x64_sys_mount+0x10/0x10

? srso_return_thunk+0x5/0x5f

? trace_irq_enable.constprop.0+0x116/0x150

? srso_return_thunk+0x5/0x5f

do_syscall_64+0x111/0x680

entry_SYSCALL_64_after_hwframe+0x77/0x7f

RIP: 0033:0x7ffacad55eae

Code: 48 8b 0d 85 1f 0f 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 49 89 ca b8 a5 00 00 8

RSP: 002b

---truncated---