[PATCH 5.15 221/279] s390/dump: fix copying to user-space of swapped kdump oldmem

[Greg Kroah-Hartman]

From: Alexander Egorenkov <egorenar@xxxxxxxxxxxxx>

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@xxxxxxxxxxxxxxx # 5.15+
Signed-off-by: Alexander Egorenkov <egorenar@xxxxxxxxxxxxx>
Reviewed-by: Marc Hartmayer <mhartmay@xxxxxxxxxxxxx>
Reviewed-by: Heiko Carstens <hca@xxxxxxxxxxxxx>
Signed-off-by: Heiko Carstens <hca@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 arch/s390/kernel/crash_dump.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- 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
 				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);