The Linux kernel dm-io subsystem had a flaw in handling DM_IO_BIO requests where do_region() rebuilt destination bios by iterating over the source bio's biovec and re-adding pages with sector-based accounting. Because vector lengths are byte granular and not necessarily sector aligned, the sector accounting truncated sub-sector fragments, causing the loop to spin indefinitely submitting empty bios and hanging I/O. The fix replaces this approach by cloning the source bio's biovec using bio_alloc_clone(), which preserves the iterator and alignment, allowing the block layer to handle splitting. This removes the per-page copy path and fixes the hang on misaligned direct I/O to dm-mirror devices.

The vulnerability could cause I/O operations to hang indefinitely when performing misaligned direct I/O to dm-mirror devices, leading to potential denial of service conditions on affected systems. There is no indication of data corruption or privilege escalation from the provided information.

A fix has been implemented in the Linux kernel to clone the source bio's biovec instead of copying it, resolving the infinite loop and I/O hang issue. Users should update to the fixed kernel version once available. Patch status is not yet confirmed in the provided data; check the official Linux kernel advisories or vendor updates for the current remediation guidance.