CVE-2024-53148

What it actually does

Partial remap_pfn_range() successes leave buffer pages mapped into userspace page tables when comedi_buf_map_put() drops the buffer reference; mappings are only cleaned later in the mmap error path, allowing dangling pfn entries.

Why it matters to the business

Systems using the comedi subsystem for data acquisition hardware face elevated risk of memory corruption or information disclosure until kernels are updated; prevalence in Linux distributions increases exposure for industrial and scientific workloads.

How an attack unfolds

An attacker triggers repeated comedi buffer mapping operations that cause some remap_pfn_range() calls to succeed before a later failure; the resulting partial mappings allow subsequent operations to access stale page table entries, potentially leading to memory corruption. Threat actors in espionage and financially motivated campaigns have targeted similar Linux kernel memory mapping flaws.

How to fix it

Upgrade the Linux kernel to commit 57f048c2d205b85e34282a9b0b0ae177e84c2f44 or later; apply the corresponding stable backports. For affected Ubuntu packages, update squid3 to 3.3.8-1ubuntu6.8 (14.04) or 3.5.12-1ubuntu7.2 (16.04) where the kernel fix is included.

How to confirm the fix worked

Verify the running kernel contains commit 57f048c2d205b85e34282a9b0b0ae177e84c2f44; confirm comedi buffer mapping error paths no longer leave partial pfn entries by reviewing page table state after injected failures.

Typical attack path

1. Obtain local access or code execution on a system with the comedi driver loaded
2. Trigger buffer allocation and mmap operations that exercise remap_pfn_range()
3. Force an error path after partial mapping success to leave dangling userspace entries
4. Reuse or manipulate the stale mappings to corrupt kernel or userspace memory

How to detect it

Search kernel logs for comedi buffer mapping failures followed by page table warnings; inspect process memory mappings after comedi mmap errors for unexpected pfn entries. Correlate with threat actor activity targeting Linux kernel memory flaws.

What your security team should do

• Prioritize kernel updates on all systems exposing the comedi driver within the next 30 days
• Review and restrict unprivileged access to comedi devices and /dev/comedi* nodes
• Monitor EPSS and KEV status for any change indicating increased exploitation