CVE-2024-35813

What it actually does

Missing bounds check on iterator allows idatas[i-1] array access when i==0, resulting in negative index and potential out-of-bounds memory read/write or kernel crash in the MMC subsystem.

Why it matters to the business

Local denial-of-service or system instability on Linux-based devices during MMC/flash operations such as firmware flashing; high downstream prevalence increases patching urgency across servers, embedded, and Android-derived systems.

How an attack unfolds

An attacker with local code execution triggers the vulnerable MMC close-ended FFU path with an iterator value of zero, causing the unchecked negative array index and subsequent memory corruption or panic; listed Android kernel RCE actor context indicates possible interest in similar kernel flaws but no public exploit exists for this specific issue.

How to fix it

Upgrade Linux kernel to 5.4.274 or later stable releases containing commit b9a7339ae403035ffe7fc37cb034b36947910f68; rebuild and reboot all affected systems; apply distribution backports where available.

How to confirm the fix worked

Verify running kernel version is at or above the fixed releases; confirm presence of the bounds check in drivers/mmc/core/ code; run regression tests exercising FFU paths and monitor for negative-index or array-out-of-bounds warnings.

Typical attack path

1. Obtain local user or process execution on target system
2. Invoke MMC operations that exercise the close-ended FFU code path
3. Force iterator i to zero so idatas[i-1] produces negative index
4. Trigger kernel memory access violation leading to crash or corruption

How to detect it

Review kernel logs (dmesg, /var/log/kern.log) for MMC-related oops, panic, or array-bounds warnings around FFU or sbc operations; correlate with process activity invoking mmc or block-layer flash utilities.

What your security team should do

• Immediately schedule kernel upgrades to 5.4.274+ across all fleets
• Prioritize systems performing MMC firmware updates or flash operations
• Add kernel version checks to vulnerability scanning and asset inventory
• Monitor for post-patch stability issues in MMC subsystem