CVE-2024-44950

What it actually does

Race condition during special register set access in sc16is7xx serial driver allows IRQ handler to read FIFO via RHR at address 0x00 while that address maps to DLL, resulting in erroneous data reads.

Why it matters to the business

Unreliable serial port operation on affected hardware can cause communication failures or system instability in embedded, industrial, or server environments using this driver, with higher urgency for organizations running unpatched kernels exposed to timing-sensitive workloads.

How an attack unfolds

An attacker triggers baud rate reconfiguration or termios changes that enable the special register set; concurrent receiver timeout or RHR interrupts then cause the IRQ handler to perform FIFO reads against the incorrectly mapped register.

How to fix it

Update the Linux kernel to a version containing commit cc6a3f35bc9b3a8da1b195420a2e8d9fdadfa831 or later; rebuild and deploy the fixed kernel image on all affected systems. For the Buildkite elastic-ci-stack-for-aws component, upgrade to version 6.7.1 or newer.

How to confirm the fix worked

Verify the running kernel contains the fix commit or is newer than the vulnerable versions; exercise sc16is7xx baud rate changes under load while monitoring for erroneous FIFO behavior or kernel warnings.

Typical attack path

1. Invoke sc16is7xx_set_termios or sc16is7xx_set_baud to access special register set
2. Allow concurrent sc16is7xx_port_irq to fire with IIR indicating RX event
3. sc16is7xx_handle_rx calls sc16is7xx_fifo_read against mapped DLL instead of RHR
4. Incorrect data or state leads to driver malfunction or crash

How to detect it

Review kernel logs for serial driver warnings or unexpected register access patterns around sc16is7xx during baud rate or termios changes; no public exploitation artifacts are known.

What your security team should do

• Apply the referenced kernel commit or distribution update immediately on all systems using sc16is7xx hardware
• Prioritize patching in environments with high serial port utilization or real-time constraints
• Monitor kernel changelogs for backports to supported stable branches