From: Markus Armbruster <armbru@redhat.com>

atoui() and get_index() pass char values to isdigit().  With a
standard isdigit(), we'd get undefined behavior when the value is
negative.  Can't happen as char is unsigned on s390x.  Even if it
ould, we're actually using isdigit() from pc-bios/s390-ccw/libc.h
here, which works fine for negative values.  Clean up anyway, just
to avoid setting a bad example.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20190418145355.21100-6-armbru@redhat.com>
[thuth: updated the commit message]
Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 pc-bios/s390-ccw/libc.c | 2 +-
 pc-bios/s390-ccw/menu.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/pc-bios/s390-ccw/libc.c b/pc-bios/s390-ccw/libc.c
index a786566c4c7b..3187923950e2 100644
--- a/pc-bios/s390-ccw/libc.c
+++ b/pc-bios/s390-ccw/libc.c
@@ -38,7 +38,7 @@ uint64_t atoui(const char *str)
     }
 
     while (*str) {
-        if (!isdigit(*str)) {
+        if (!isdigit(*(unsigned char *)str)) {
             break;
         }
         val = val * 10 + *str - '0';
diff --git a/pc-bios/s390-ccw/menu.c b/pc-bios/s390-ccw/menu.c
index 82a4ae631597..ce3815b2010d 100644
--- a/pc-bios/s390-ccw/menu.c
+++ b/pc-bios/s390-ccw/menu.c
@@ -134,7 +134,7 @@ static int get_index(void)
 
     /* Check for erroneous input */
     for (i = 0; i < len; i++) {
-        if (!isdigit(buf[i])) {
+        if (!isdigit((unsigned char)buf[i])) {
             return -1;
         }
     }
-- 
2.20.1