CVE-2026-80550

Summary

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.

Affected Software

VendorProductVersion RangeStatus
LinuxLinux0a19e61e6d4c6192077ead760ba0a2d350987d4c < 0282fb1c4b638eecfe2cc558092c460911d8f7e2affected
LinuxLinux0a19e61e6d4c6192077ead760ba0a2d350987d4c < 907adc667d902fafbdb2d740d57b55bd025dc4cdaffected
LinuxLinux0a19e61e6d4c6192077ead760ba0a2d350987d4c < f20be33d093ce7630c17ff7ed93caf7eaf8ac1a3affected
LinuxLinux0a19e61e6d4c6192077ead760ba0a2d350987d4c < af3f80ca4c8b17f20f9e588def076288fdb49e65affected
LinuxLinux0a19e61e6d4c6192077ead760ba0a2d350987d4c < 499a8a66b1598bfab97182aed15e0f1646074a3daffected
LinuxLinux0a19e61e6d4c6192077ead760ba0a2d350987d4c < 4c2e1d359d7a2b82cdf3254e4e480af9417f99fbaffected
LinuxLinux0a19e61e6d4c6192077ead760ba0a2d350987d4c < d5d096cd9369e986d4e5153baa86b8b35c283e09affected
LinuxLinux0a19e61e6d4c6192077ead760ba0a2d350987d4c < a005b7f1a491ffda61bff0fd0f6548f8986fb977affected
LinuxLinux4.12affected
LinuxLinux0 < 4.12unaffected
LinuxLinux5.10.266 <= 5.10.*unaffected
LinuxLinux5.15.217 <= 5.15.*unaffected
LinuxLinux6.1.184 <= 6.1.*unaffected
LinuxLinux6.6.153 <= 6.6.*unaffected
LinuxLinux6.12.105 <= 6.12.*unaffected
LinuxLinux6.18.46 <= 6.18.*unaffected
LinuxLinux7.1.10 <= 7.1.*unaffected
LinuxLinux7.2 <= *unaffected

Weaknesses

References