CVE-2026-31482 PUBLISHED

s390/entry: Scrub r12 register on kernel entry

Assigner: Linux
Reserved: 09.03.2026 Published: 22.04.2026 Updated: 22.04.2026

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.

Product Status

Vendor Linux
Product Linux
Versions Default: unaffected
  • affected from f33f2d4c7c80c641f6ca3dfe5e7dfe1f91543780 to a58d298a83a3a9b7ca99ded9d60a1e77231159ef (excl.)
  • affected from f33f2d4c7c80c641f6ca3dfe5e7dfe1f91543780 to 95c899cd791803a5bf7b73e5994fbbe1cc1a9c36 (excl.)
  • affected from f33f2d4c7c80c641f6ca3dfe5e7dfe1f91543780 to 7f4e3233faa8470dd0627bc49b2809f2bfebd909 (excl.)
  • affected from f33f2d4c7c80c641f6ca3dfe5e7dfe1f91543780 to 99a8b420f3f0e162eb9c9c9253929d4d23f9bd30 (excl.)
  • affected from f33f2d4c7c80c641f6ca3dfe5e7dfe1f91543780 to 0738d395aab8fae3b5a3ad3fc640630c91693c27 (excl.)
Vendor Linux
Product Linux
Versions Default: affected
  • Version 6.4 is affected
  • unaffected from 0 to 6.4 (excl.)
  • unaffected from 6.6.131 to 6.6.* (incl.)
  • unaffected from 6.12.80 to 6.12.* (incl.)
  • unaffected from 6.18.21 to 6.18.* (incl.)
  • unaffected from 6.19.11 to 6.19.* (incl.)
  • unaffected from 7.0 to * (incl.)

References