CVE-2024-43877

What it actually does

Missing validation of DMA mapping result allows SG_length to remain zero, causing out-of-bounds access into SGarray when the driver later indexes SGarray[SG_length-1].

Why it matters to the business

Systems using the ivtv driver may experience kernel instability or crashes during media capture operations; widespread Linux distributions are affected until patched kernels are deployed.

How an attack unfolds

An attacker with local access or the ability to influence DMA operations triggers a DMA mapping failure in the ivtv PCI driver; the subsequent unchecked use of a zero SG_length value produces an out-of-bounds memory access that can be leveraged for denial of service or, under specific conditions, memory corruption.

How to fix it

Apply the upstream fix contained in commit 38f72c7e7c6b55614f9407555fd5ce9d019b0fa4 or later; rebuild and deploy the updated kernel to all affected hosts. Reboot is required after installation.

How to confirm the fix worked

Confirm the presence of the early-return check after DMA mapping in drivers/media/pci/ivtv/ivtv-driver.c and verify the running kernel contains commit 38f72c7e7c6b55614f9407555fd5ce9d019b0fa4 or an equivalent backport.

Typical attack path

1. Obtain local execution or trigger media device initialization on an affected ivtv-based system
2. Force or wait for a DMA mapping failure that sets SG_length to zero
3. Allow the driver to reach the SGarray indexing code without the added validation
4. Trigger out-of-bounds access leading to kernel panic or controlled memory corruption

How to detect it

Review kernel logs for ivtv-related DMA warnings or out-of-bounds access oops messages; examine dmesg and syslog for entries referencing ivtv and SG_length or DMA failures around the time of any unexpected reboots.

• ivtv.*dma mapping failed
• SG_length
• out of bounds access
• ivtv-driver.c

What your security team should do

• Prioritize kernel updates on systems exposing ivtv hardware within the next patching cycle
• Monitor vendor advisories for distribution-specific backports of commit 38f72c7e7c6b55614f9407555fd5ce9d019b0fa4
• Restrict untrusted local access to media devices until patches are applied