CVE-2024-26706

What it actually does

The parisc exception handler for user-space memory accesses may store -EFAULT into an unintended register when the compiler selects a register other than the one expected by ASM_EXCEPTIONTABLE_REG, resulting in corruption of unrelated data in functions such as emulate_ldd().

Why it matters to the business

On PA-RISC Linux systems, workloads that perform user-space memory accesses under certain compiler decisions can experience silent data corruption or application instability, increasing operational risk and potential data-integrity incidents until systems are updated.

How an attack unfolds

An attacker with local access triggers a page fault in a code path such as emulate_ldd() that uses the broken exception-table entry; because the fault handler writes to the wrong register, attacker-controlled or adjacent data is corrupted, which may be leveraged for further reliability or integrity attacks.

How to fix it

Upgrade the Linux kernel to a version containing commit 23027309b099ffc4efca5477009a11dccbdae592 or later; rebuild and reboot with the corrected __ex_table layout.

How to confirm the fix worked

Confirm the running kernel contains commit 23027309b099ffc4efca5477009a11dccbdae592; inspect the __ex_table entries for the added 32-bit word encoding the error-code register; run regression tests that exercise emulate_ldd() and user-space copy paths.

Typical attack path

1. Obtain local code execution on a PA-RISC Linux system
2. Force a user-space memory access that hits the faulty exception-table path
3. Trigger the page-fault handler so it overwrites an unintended register
4. Observe or exploit resulting data corruption

How to detect it

Review kernel logs for unexpected -EFAULT handling or register-related anomalies on parisc; correlate any application crashes or checksum mismatches with parisc exception paths; no public exploit artifacts are known.

What your security team should do

• Prioritize kernel updates on all PA-RISC systems within the next maintenance window
• Add the fixed commit ID to internal kernel build and deployment pipelines
• Monitor for any reports of data corruption on parisc hardware until patches are applied