s390/dump: fix copying to user-space of swapped kdump oldmem

commit 3b90954419d4c05651de9cce6d7632bcf6977678 upstream.

This commit fixes a bug introduced by commit e9e7870f90e3 ("s390/dump:
introduce boot data 'oldmem_data'").
OLDMEM_BASE was mistakenly replaced by oldmem_data.size instead of
oldmem_data.start.

This bug caused the following error during kdump:
kdump.sh[878]: No program header covering vaddr 0x3434f5245found kexec bug?

Fixes: e9e7870f90e3 ("s390/dump: introduce boot data 'oldmem_data'")
Cc: stable@vger.kernel.org # 5.15+
Signed-off-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Reviewed-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/s390/kernel/crash_dump.c b/arch/s390/kernel/crash_dump.c
index d72a6df..785d54c 100644 (file)
--- a/arch/s390/kernel/crash_dump.c
+++ b/arch/s390/kernel/crash_dump.c
@@ -191,8 +191,8 @@ static int copy_oldmem_user(void __user *dst, void *src, size_t count)
                                return rc;
                } else {
                        /* Check for swapped kdump oldmem areas */
-                       if (oldmem_data.start && from - oldmem_data.size < oldmem_data.size) {
-                               from -= oldmem_data.size;
+                       if (oldmem_data.start && from - oldmem_data.start < oldmem_data.size) {
+                               from -= oldmem_data.start;
                                len = min(count, oldmem_data.size - from);
                        } else if (oldmem_data.start && from < oldmem_data.size) {
                                len = min(count, oldmem_data.size - from);