CVE-2023-53683

What it actually does

The hfsplus_cat_read_inode and hfsplus_cat_write_inode functions contain WARN_ON() checks that fire on bogus inode lengths supplied by a crafted HFS+ filesystem image, resulting in a kernel panic.

Why it matters to the business

Local users or automated processes that mount untrusted HFS+ images can trigger system crashes, causing denial of service and potential data loss or corruption on affected Linux systems.

How an attack unfolds

An attacker prepares a malicious HFS+ filesystem image containing invalid catalog inode length values, then causes a vulnerable kernel to process the image (via mount or similar operations), triggering the WARN_ON() and forcing a kernel panic.

How to fix it

Upgrade the Linux kernel to a fixed version such as 4.14.316 or apply commit 61af77acd039ffd221bf7adf0dc95d0a4d377505 that removes the WARN_ON() calls; avoid mounting untrusted HFS+ images until patched.

How to confirm the fix worked

Verify the running kernel version is at or above a fixed release; attempt to mount a test image containing bogus lengths and confirm no panic occurs.

Typical attack path

1. Create or obtain a crafted HFS+ filesystem image with invalid inode lengths
2. Gain local access or convince a user/process to mount the image
3. Trigger hfsplus_cat_read_inode or hfsplus_cat_write_inode processing
4. Force kernel panic via the WARN_ON()

How to detect it

Search kernel logs and crash dumps for hfsplus-related WARN_ON() or panic messages; examine audit or mount logs for unexpected HFS+ volume activity.

• hfsplus_cat_read_inode
• hfsplus_cat_write_inode
• WARN_ON.*hfsplus

What your security team should do

• Prioritize kernel upgrades on all systems that may process HFS+ volumes
• Restrict mounting of removable or untrusted filesystems via policy or mount options
• Monitor for kernel oops/panic reports referencing hfsplus
• Review and update any automated backup or forensic workflows that handle legacy HFS+ images