JIRA: https://issues.redhat.com/browse/RHEL-113557
CVE: CVE-2025-39694
Y-Commit: 430fa71027b6ac9bb0ce5532b8d0676777d4219a
s390/sclp: Fix SCCB present check
Tracing code called by the SCLP interrupt handler contains early exits
if the SCCB address associated with an interrupt is NULL. This check is
performed after physical to virtual address translation.
If the kernel identity mapping does not start at address zero, the
resulting virtual address is never zero, so that the NULL checks won't
work. Subsequently this may result in incorrect accesses to the first
page of the identity mapping.
Fix this by introducing a function that handles the NULL case before
address translation.
Fixes: ada1da31ce34 ("s390/sclp: sort out physical vs virtual pointers usage")
Cc: stable@vger.kernel.org
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
(cherry picked from commit 430fa71027b6ac9bb0ce5532b8d0676777d4219a)
Signed-off-by: CKI Backport Bot <cki-ci-bot+cki-gitlab-backport-bot@redhat.com>
43725bdb9c