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

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Message-Id: <20211124115726.369085216@linuxfoundation.org>
Date:   Wed, 24 Nov 2021 12:58:28 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Alexander Egorenkov <egorenar@...ux.ibm.com>,
        Marc Hartmayer <mhartmay@...ux.ibm.com>,
        Heiko Carstens <hca@...ux.ibm.com>
Subject: [PATCH 5.15 221/279] s390/dump: fix copying to user-space of swapped kdump oldmem

From: Alexander Egorenkov <egorenar@...ux.ibm.com>

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@...r.kernel.org # 5.15+
Signed-off-by: Alexander Egorenkov <egorenar@...ux.ibm.com>
Reviewed-by: Marc Hartmayer <mhartmay@...ux.ibm.com>
Reviewed-by: Heiko Carstens <hca@...ux.ibm.com>
Signed-off-by: Heiko Carstens <hca@...ux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 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);