CVE-2026-80550

Description

In the Linux kernel, the following vulnerability has been resolved: s390/vfio_ccw: Fix out of bounds check on CCW array The routine ccwchain_calc_length() counts the number of channel command words (CCWs) that are chained together in a single channel program, and rejects anything larger than CCWCHAIN_LEN_MAX (256) CCWs. The loop itself is "do..while (count < 257)", and while the logic in is_cpa_within_range() correctly adjusts between the 0-index array of CCWs and the count of CCWs starting at 1, this means it would look at a possible 257th CCW before ending the loop and (correctly) returning an error. Fix this by restructuring the loop to break as soon as 256 CCWs (thus indexes 0-255) are examined, without looking at memory outside the range.

References

• https://git.kernel.org/stable/c/0282fb1c4b638eecfe2cc558092c460911d8f7e2
• https://git.kernel.org/stable/c/499a8a66b1598bfab97182aed15e0f1646074a3d
• https://git.kernel.org/stable/c/4c2e1d359d7a2b82cdf3254e4e480af9417f99fb
• https://git.kernel.org/stable/c/907adc667d902fafbdb2d740d57b55bd025dc4cd
• https://git.kernel.org/stable/c/a005b7f1a491ffda61bff0fd0f6548f8986fb977