CVE-2024-26945

What it actually does

Division by zero in rebalance_wq_table() when nr_cpus is less than nr_iaa during IAA crypto accelerator initialization, resulting in a kernel crash.

Why it matters to the business

Unexpected system crashes or denial of service on Linux systems using the IAA crypto driver, potentially affecting availability of servers or devices with specific accelerator configurations; high ecosystem prevalence in the Linux kernel increases exposure across many distributions.

How an attack unfolds

An attacker with local access loads or configures the iaa crypto module under conditions where nr_cpus < nr_iaa (or nr_iaa == 0), triggering the divide-by-zero during workqueue rebalancing; no widespread threat actor exploitation observed despite mentions of Android kernel issues.

How to fix it

Update to Linux kernel version 6.8.3 or apply the commit a5ca1be7f9817de4e93085778b3ee2219bdc2664 in the stable git tree; ensure cpus_per_iaa is forced to at least 1 in the driver code.

How to confirm the fix worked

Verify the presence of the fix commit or kernel version 6.8.3+; test iaa module loading under nr_cpus < nr_iaa conditions to confirm no divide-by-zero occurs.

Typical attack path

1. Obtain local access to the target system
2. Trigger iaa module initialization with nr_cpus less than nr_iaa
3. Cause rebalance_wq_table() to perform division by zero
4. Induce kernel panic or crash

How to detect it

Search kernel logs and dmesg for divide-by-zero faults or panics referencing iaa or rebalance_wq_table; review module load events around crash times.

What your security team should do

• Prioritize upgrading affected kernels to 6.8.3 or patched equivalents within 30 days
• Monitor for kernel oops or panic logs involving rebalance_wq_table
• Audit systems for IAA crypto accelerator usage and restrict module loading where possible