linux-cve-announce - CVE-2023-53862: hfs: fix missing hfs_bnode_get() in __hfs_bnode

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Message-ID: <2025120905-CVE-2023-53862-81d5@gregkh>
Date: Tue,  9 Dec 2025 10:31:46 +0900
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2023-53862: hfs: fix missing hfs_bnode_get() in __hfs_bnode_create

From: Greg Kroah-Hartman <gregkh@...nel.org>

Description
===========

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

hfs: fix missing hfs_bnode_get() in __hfs_bnode_create

Syzbot found a kernel BUG in hfs_bnode_put():

 kernel BUG at fs/hfs/bnode.c:466!
 invalid opcode: 0000 [#1] PREEMPT SMP KASAN
 CPU: 0 PID: 3634 Comm: kworker/u4:5 Not tainted 6.1.0-rc7-syzkaller-00190-g97ee9d1c1696 #0
 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
 Workqueue: writeback wb_workfn (flush-7:0)
 RIP: 0010:hfs_bnode_put+0x46f/0x480 fs/hfs/bnode.c:466
 Code: 8a 80 ff e9 73 fe ff ff 89 d9 80 e1 07 80 c1 03 38 c1 0f 8c a0 fe ff ff 48 89 df e8 db 8a 80 ff e9 93 fe ff ff e8 a1 68 2c ff <0f> 0b e8 9a 68 2c ff 0f 0b 0f 1f 84 00 00 00 00 00 55 41 57 41 56
 RSP: 0018:ffffc90003b4f258 EFLAGS: 00010293
 RAX: ffffffff825e318f RBX: 0000000000000000 RCX: ffff8880739dd7c0
 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
 RBP: ffffc90003b4f430 R08: ffffffff825e2d9b R09: ffffed10045157d1
 R10: ffffed10045157d1 R11: 1ffff110045157d0 R12: ffff8880228abe80
 R13: ffff88807016c000 R14: dffffc0000000000 R15: ffff8880228abe00
 FS:  0000000000000000(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 00007fa6ebe88718 CR3: 000000001e93d000 CR4: 00000000003506f0
 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
 Call Trace:
  <TASK>
  hfs_write_inode+0x1bc/0xb40
  write_inode fs/fs-writeback.c:1440 [inline]
  __writeback_single_inode+0x4d6/0x670 fs/fs-writeback.c:1652
  writeback_sb_inodes+0xb3b/0x18f0 fs/fs-writeback.c:1878
  __writeback_inodes_wb+0x125/0x420 fs/fs-writeback.c:1949
  wb_writeback+0x440/0x7b0 fs/fs-writeback.c:2054
  wb_check_start_all fs/fs-writeback.c:2176 [inline]
  wb_do_writeback fs/fs-writeback.c:2202 [inline]
  wb_workfn+0x827/0xef0 fs/fs-writeback.c:2235
  process_one_work+0x877/0xdb0 kernel/workqueue.c:2289
  worker_thread+0xb14/0x1330 kernel/workqueue.c:2436
  kthread+0x266/0x300 kernel/kthread.c:376
  ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
  </TASK>

The BUG_ON() is triggered at here:

/* Dispose of resources used by a node */
void hfs_bnode_put(struct hfs_bnode *node)
{
	if (node) {
 		<skipped>
 		BUG_ON(!atomic_read(&node->refcnt)); <- we have issue here!!!!
 		<skipped>
 	}
}

By tracing the refcnt, I found the node is created by hfs_bmap_alloc()
with refcnt 1.  Then the node is used by hfs_btree_write().  There is a
missing of hfs_bnode_get() after find the node.  The issue happened in
following path:

<alloc>
 hfs_bmap_alloc
   hfs_bnode_find
     __hfs_bnode_create   <- allocate a new node with refcnt 1.
   hfs_bnode_put          <- decrease the refcnt

<write>
 hfs_btree_write
   hfs_bnode_find
     __hfs_bnode_create
       hfs_bnode_findhash <- find the node without refcnt increased.
   hfs_bnode_put	  <- trigger the BUG_ON() since refcnt is 0.

The Linux kernel CVE team has assigned CVE-2023-53862 to this issue.


Affected and fixed versions
===========================

	Fixed in 4.14.308 with commit 062af3e9930762d1fd22946748d34e0d859e4a8e
	Fixed in 4.19.276 with commit 3a9065a33988c02789722be612f7c42fb8ebbb22
	Fixed in 5.4.235 with commit eda6879272e4df5456afc36642052ea066f58410
	Fixed in 5.10.173 with commit dc9f78b6d254427a06e568f2887b1011ef3143ef
	Fixed in 5.15.99 with commit 2cab8db14566cf6a516c1f103a60cf6b7f54b1e5
	Fixed in 6.1.16 with commit 8140cdc57bc5844cd5e1392673ec2dbf8fdc6940
	Fixed in 6.2.3 with commit 38d72e6604b9f96dffcc0565090cc01622a37b2a
	Fixed in 6.3 with commit a9dc087fd3c484fd1ed18c5efb290efaaf44ce03

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2023-53862
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	fs/hfs/bnode.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/062af3e9930762d1fd22946748d34e0d859e4a8e
	https://git.kernel.org/stable/c/3a9065a33988c02789722be612f7c42fb8ebbb22
	https://git.kernel.org/stable/c/eda6879272e4df5456afc36642052ea066f58410
	https://git.kernel.org/stable/c/dc9f78b6d254427a06e568f2887b1011ef3143ef
	https://git.kernel.org/stable/c/2cab8db14566cf6a516c1f103a60cf6b7f54b1e5
	https://git.kernel.org/stable/c/8140cdc57bc5844cd5e1392673ec2dbf8fdc6940
	https://git.kernel.org/stable/c/38d72e6604b9f96dffcc0565090cc01622a37b2a
	https://git.kernel.org/stable/c/a9dc087fd3c484fd1ed18c5efb290efaaf44ce03