CVE-2026-31482

Summary

In the Linux kernel, the following vulnerability has been resolved:

s390/entry: Scrub r12 register on kernel entry

Before commit f33f2d4c7c80 ("s390/bp: remove TIF_ISOLATE_BP"), all entry handlers loaded r12 with the current task pointer (lg %r12,__LC_CURRENT) for use by the BPENTER/BPEXIT macros. That commit removed TIF_ISOLATE_BP, dropping both the branch prediction macros and the r12 load, but did not add r12 to the register clearing sequence.

Add the missing xgr %r12,%r12 to make the register scrub consistent across all entry points.

Affected Software

VendorProductVersion RangeStatus
LinuxLinuxf33f2d4c7c80c641f6ca3dfe5e7dfe1f91543780 < a58d298a83a3a9b7ca99ded9d60a1e77231159efaffected
LinuxLinuxf33f2d4c7c80c641f6ca3dfe5e7dfe1f91543780 < 95c899cd791803a5bf7b73e5994fbbe1cc1a9c36affected
LinuxLinuxf33f2d4c7c80c641f6ca3dfe5e7dfe1f91543780 < 7f4e3233faa8470dd0627bc49b2809f2bfebd909affected
LinuxLinuxf33f2d4c7c80c641f6ca3dfe5e7dfe1f91543780 < 99a8b420f3f0e162eb9c9c9253929d4d23f9bd30affected
LinuxLinuxf33f2d4c7c80c641f6ca3dfe5e7dfe1f91543780 < 0738d395aab8fae3b5a3ad3fc640630c91693c27affected
LinuxLinux6.4affected
LinuxLinux0 < 6.4unaffected
LinuxLinux6.6.131 <= 6.6.*unaffected
LinuxLinux6.12.80 <= 6.12.*unaffected
LinuxLinux6.18.21 <= 6.18.*unaffected
LinuxLinux6.19.11 <= 6.19.*unaffected
LinuxLinux7.0 <= *unaffected

Weaknesses

References