CVE-2023-52458

What it actually does

Missing alignment check on partition length versus logical block size before add/resize allows creation of partitions whose final sector triggers bio_truncate adjustment and subsequent IO error; when integrity metadata is present the same path dereferences a null bio integrity pointer.

Why it matters to the business

Systems using disks with logical block sizes larger than 512 bytes can experience unexpected read failures or kernel crashes during normal partition I/O, increasing downtime and operational risk on widely deployed Linux kernels.

How an attack unfolds

An attacker with local access crafts or resizes a partition whose length is not a multiple of the device logical block size, then triggers read I/O that reaches the last sector; the resulting bio size adjustment either produces an error or, with integrity enabled, triggers the null dereference.

How to fix it

Update the Linux kernel to commit 8f6dfa1f1efe6dcca2d43e575491d8fcbe922f62 or later stable release containing the alignment check; rebuild and reboot with the patched kernel.

How to confirm the fix worked

Confirm the running kernel contains commit 8f6dfa1f1efe6dcca2d43e575491d8fcbe922f62; attempt partition creation with non-aligned length on a >512-byte block device and verify the operation is now rejected before the bio path.

Typical attack path

1. Obtain local user access on target system
2. Identify block device with logical block size > 512 bytes
3. Use partition utilities to create or resize a partition with unaligned length
4. Perform read operations that reach the final sector of the partition
5. Trigger kernel path that calls bio_truncate or bio_integrity_free

How to detect it

Review kernel logs for bio_truncate warnings or null pointer dereference traces involving bio_integrity_free on block devices; correlate with partition resize or creation events in dmesg or audit logs.

What your security team should do

• Prioritize kernel updates on all systems exposing block devices with logical block sizes > 512 bytes
• Audit custom partition scripts and tools for alignment assumptions
• Monitor vendor advisories for backported fixes in distribution kernels