CVE-2023-52790

What it actually does

Out-of-bounds slot allocation in swiotlb_area_find_slots() when a transient IO TLB pool is smaller than IO_TLB_SEGSIZE under CONFIG_SWIOTLB_DYNAMIC, allowing writes past the end of the buffer and resulting in memory corruption.

Why it matters to the business

Linux systems using dynamic SWIOTLB may experience kernel crashes, unexpected reboots, or potential privilege escalation and data exposure on servers and embedded devices that rely on DMA bounce buffering.

How an attack unfolds

An attacker with local access crafts DMA operations that force the kernel to create a transient swiotlb pool whose slot count is not a multiple of IO_TLB_SEGSIZE; subsequent calls to swiotlb_area_find_slots() then index past the pool boundary, corrupting adjacent kernel memory.

How to fix it

Upgrade the Linux kernel to a fixed release containing commit ce7612496a4ba6068bc68aa1fa9d947dadb4ad9b or later stable versions such as 6.6.3 and beyond; rebuild and reboot with the patched kernel image.

How to confirm the fix worked

Confirm the running kernel contains the fix by checking git commit or version string; run kernel selftests for swiotlb and verify no transient-pool size assumptions remain; monitor dmesg for swiotlb allocation warnings after upgrade.

Typical attack path

1. Obtain local code execution on a Linux system with CONFIG_SWIOTLB_DYNAMIC enabled
2. Trigger device or driver code paths that allocate a transient swiotlb pool smaller than IO_TLB_SEGSIZE
3. Perform DMA operations that invoke swiotlb_area_find_slots() repeatedly
4. Cause out-of-bounds writes that corrupt kernel structures
5. Escalate to ring-0 privileges or induce denial of service

How to detect it

Review kernel logs for swiotlb allocation errors or oops traces involving swiotlb_area_find_slots; correlate with processes performing unusual DMA operations; examine crash dumps for out-of-bounds accesses in the swiotlb module.

What your security team should do

• Prioritize patching production kernels within 30 days given the memory-corruption class
• Audit boot configurations for systems that enable CONFIG_SWIOTLB_DYNAMIC and disable if DMA bounce buffers are unnecessary
• Include the fixed kernel in the next maintenance window for all distributions shipping affected versions