CVE-2024-53233

What it actually does

Incorrect use of symbol_put() with a pointer instead of the symbol's identifying string in utf8_load() error path triggers a kernel BUG when an unsupported UTF-8 version is requested.

Why it matters to the business

Unexpected kernel crashes on Linux systems that attempt to load unsupported Unicode data tables, causing downtime and potential loss of availability for dependent services.

How an attack unfolds

An attacker supplies or triggers a request for an unsupported UTF-8 version to utf8_load(), causing the function to enter the error path and invoke symbol_put() incorrectly, resulting in an invalid opcode exception and kernel panic.

How to fix it

Update the Linux kernel to a version containing commit 4387cef540f36c2c9297460758cc2438305a24a0 or later; apply the corresponding package updates for affected distributions.

How to confirm the fix worked

Verify the running kernel contains the fix commit or is at a patched version; attempt to load an unsupported UTF-8 version in a test environment and confirm no BUG occurs.

Typical attack path

1. Identify or control a code path that invokes utf8_load() with an unsupported version string
2. Trigger the call to enter the error handling branch
3. Observe the resulting kernel BUG and system crash

How to detect it

Search kernel logs for the string 'kernel BUG at kernel/module/main.c' combined with __symbol_put and utf8_load call traces; inspect module loading events around the time of any sudden reboots or panics.

• kernel BUG at kernel/module/main.c:786
• __symbol_put+0x93/0xb0
• utf8_load+0xf8/0x150

What your security team should do

• Prioritize kernel updates on all production Linux systems within the next patching cycle
• Monitor for any reports of unicode-related crashes in logs
• Review Unicode handling code in custom modules or applications for similar symbol usage patterns