CVE Catalog

CVE-2026-89578

Low risk· EPSS 10%
Published: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.20%

10th percentile - higher than 10% of all known CVEs

Summary

The Linux kernel's dm-io module rebuilt destination bios for DM_IO_BIO requests by copying the source biovec, which with non-sector-aligned vector lengths (e.g. misaligned O_DIRECT buffers) could lose a sub-sector fragment and hang I/O. The fix clones the source biovec via bio_alloc_clone() and remaps it to the target device, eliminating manual page copying.

Risk Assessment

Misaligned direct I/O to a dm-mirror device can hang I/O operations, causing service unavailability and potential data loss. The issue affects systems using dm-mirror with misaligned O_DIRECT buffers.

Recommendation

Update the Linux kernel to a version containing the fix that clones the source biovec in dm-io. Until the update, avoid misaligned direct I/O on dm-mirror devices.

Other vulnerabilities in Linux kernel

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Original NVD description (English source)

In the Linux kernel, the following vulnerability has been resolved: dm-io: clone the source bio instead of copying its biovec For DM_IO_BIO requests, do_region() built each destination bio by walking the source bio's biovec and re-adding the pages one at a time, tracking the remaining transfer in sectors. The vector lengths are byte granular and need not be sector aligned (e.g. a misaligned O_DIRECT buffer split across pages), so the sector-based accounting could lose a sub-sector fragment: to_sector() truncated the remainder and the outer loop spun forever submitting empty bios, hanging the I/O. There is no need to rebuild the biovec at all. The destination reads into (or writes from) exactly the same pages as the source bio, so the bio can simply clone the source's biovec with bio_alloc_clone() and remap it to the target device. The clone inherits the source's iterator and alignment, and the block layer splits it to the target's limits on submission, so the whole region maps to a single cloned bio with no manual page copying or sector accounting. This removes the per-page copy path (and its open-coded bvec dpages helpers) for bio-backed I/O and fixes the hang on misaligned direct I/O to a dm-mirror device. Page-list, vma and kmem sources keep the existing copy path.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS