CVE-2026-31482

Description

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.

References

• https://git.kernel.org/stable/c/0738d395aab8fae3b5a3ad3fc640630c91693c27
• https://git.kernel.org/stable/c/7f4e3233faa8470dd0627bc49b2809f2bfebd909
• https://git.kernel.org/stable/c/95c899cd791803a5bf7b73e5994fbbe1cc1a9c36
• https://git.kernel.org/stable/c/99a8b420f3f0e162eb9c9c9253929d4d23f9bd30
• https://git.kernel.org/stable/c/a58d298a83a3a9b7ca99ded9d60a1e77231159ef