CVE-2024-57910

What it actually does

The vcnl4035 IIO driver allocates a local u16 buffer aligned to 8 bytes for triggered buffer reads but fails to zero-initialize it before a regmap_read() that only populates two bytes, leaving at least four bytes of uninitialized kernel stack data that are then copied to userspace.

Why it matters to the business

Attackers with local access can read leftover kernel memory that may contain credentials, addresses, or other sensitive data; the affected code is present in many Linux distributions and embedded devices, increasing the chance of information disclosure across large fleets.

How an attack unfolds

An attacker with local access opens the vcnl4035 IIO device, configures a triggered buffer, and repeatedly reads from the buffer file descriptor; each read returns the partially uninitialized 8-byte structure, allowing the attacker to harvest whatever stack data was left behind.

How to fix it

Upgrade the Linux kernel to commit 62fb9874f5da54fdb243003b386128037319b219 or later; rebuild and reboot with the patched kernel; if immediate update is impossible, restrict unprivileged access to IIO devices via udev rules or SELinux policies.

How to confirm the fix worked

Confirm the running kernel contains commit 62fb9874f5da54fdb243003b386128037319b219 by checking /proc/version or git log; attempt to trigger the buffer and verify that all eight bytes are now consistently zeroed in userspace reads.

Typical attack path

1. Obtain local user access on a system running an affected kernel
2. Locate and open the vcnl4035 sysfs or IIO device node
3. Enable triggered buffering for the light sensor channel
4. Perform repeated reads on the buffer character device
5. Parse returned data to extract uninitialized bytes from previous stack frames

How to detect it

Review kernel audit logs or eBPF traces for unusual numbers of reads against vcnl4035 buffer devices by non-root processes; examine memory dumps or core files for patterns of repeated 8-byte reads returning non-zero values in the upper bytes.

What your security team should do

• Prioritize kernel updates on any system exposing IIO sensors to untrusted users
• Audit local user permissions on /dev/iio* and /sys/bus/iio devices
• Monitor EPSS and kernel mailing list for related uninitialized-memory issues
• Apply the same patch across all downstream distributions and embedded images