CVE-2019-18809

What it actually does

Memory leak in af9005_identify_state() in the Linux kernel's DVB-USB driver allows repeated calls to consume unbounded kernel memory.

Why it matters to the business

Systems with affected USB tuner hardware may experience gradual memory exhaustion, leading to degraded performance or forced reboots after prolonged operation.

How an attack unfolds

An attacker with physical access repeatedly inserts a compatible USB DVB device to trigger the identify_state function, exhausting available memory until the system becomes unresponsive.

How to fix it

Update the Linux kernel to the commit 2289adbfa559050d2a38bcd9caac1c18b800e928 or later; rebuild and reboot with the patched kernel on affected systems.

How to confirm the fix worked

Verify the running kernel contains commit 2289adbfa559050d2a38bcd9caac1c18b800e928 and confirm the af9005 driver no longer exhibits unbounded allocation under repeated device identification.

Typical attack path

1. Obtain physical access to the target system
2. Insert a USB DVB device that exercises the af9005 driver
3. Repeat insertion or trigger device initialization multiple times
4. Observe progressive kernel memory consumption until denial of service

How to detect it

Review kernel memory statistics and dmesg logs for repeated af9005 driver allocations; correlate with USB device insertion events showing increasing slab or page cache consumption.

What your security team should do

• Apply the kernel fix immediately on any systems exposing the af9005 driver
• Disable the af9005 module if the hardware is not required
• Monitor memory usage trends on systems with USB DVB hardware