Out of Bounds Vulnerability in Linux Kernel Affecting s390/vfio_ccw

CVE-2026-80550

What is CVE-2026-80550?

A vulnerability in the Linux kernel's handling of channel command words (CCWs) in the s390/vfio_ccw driver allows for out-of-bounds memory access. The flaw arises from an incorrect loop condition in the ccwchain_calc_length() function, which attempts to examine memory beyond valid index ranges, specifically when counting CCWs in a single channel program. By failing to properly validate the number of CCWs, the function risks exposing the system to potential memory corruption which could lead to unpredictable behavior or security breaches. This issue has been addressed by restructuring the loop to prevent such out-of-bounds checks which could access beyond the defined limits.

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