CVE-2024-50291

What it actually does

Missing validation of buffer index in dvb_vb2_expbuf() permits access to invalid or uninitialized buffers in the DVB video buffer handling path.

Why it matters to the business

Kernel instability, crashes, or memory corruption on systems using DVB media subsystems can disrupt broadcast, streaming, or embedded Linux devices; prevalence across kernel trees increases exposure for distributions and downstream products.

How an attack unfolds

An attacker supplies an out-of-range buffer index to dvb_vb2_expbuf() from userspace; without the index check the call proceeds to invalid memory access, enabling out-of-bounds read/write or use of uninitialized data. Threat actors noted in kernel out-of-bounds and uninitialized-resource campaigns could chain this primitive for local privilege escalation or denial of service.

How to fix it

Upgrade to a kernel containing commit 721c37af0355cc0b540909c57fd7930dc99c72d8 or the equivalent fixed packages: activemq 5.6.0+dfsg-1+deb7u3build0.14.04.1 on Ubuntu 14.04 LTS and 5.13.2+dfsg-2ubuntu0.1~esm1 on Ubuntu Pro 16.04 LTS.

How to confirm the fix worked

Confirm the running kernel contains the cited commit or patched package versions; exercise dvb_vb2_expbuf() with deliberately invalid indices and verify the call is rejected before buffer access occurs.

Typical attack path

1. Locate a system running a vulnerable Linux kernel with DVB-core enabled
2. Obtain or craft a userspace process that calls dvb_vb2_expbuf() with a malicious index
3. Trigger the call to bypass the absent bounds check
4. Leverage resulting memory corruption or information leak for further exploitation

How to detect it

Inspect kernel logs for dvb-core related oops or warnings mentioning buffer index or vb2_expbuf; correlate with process activity invoking DVB ioctls on unpatched kernels.

What your security team should do

• Apply the listed kernel updates on all affected systems without delay
• Prioritize patching where DVB or media subsystems are enabled
• Review and restrict untrusted userspace access to DVB devices until patched
• Monitor EPSS trend and kernel exploit activity for any increase in observed attempts