[RFC PATCH 2/6] initramfs: avoid memcpy for hex header fields

[David Disseldorp <ddiss@suse.de>]

newc/crc cpio headers contain a bunch of 8-character hexadecimal fields
which we convert via simple_strtoul(), following memcpy() into a
zero-terminated stack buffer. The new simple_strntoul() helper allows us
to pass in max_chars=8 to avoid zero-termination and memcpy().

Signed-off-by: David Disseldorp <ddiss@suse.de>
---
 init/initramfs.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/init/initramfs.c b/init/initramfs.c
index bc911e466d5bb..c35600d49a50a 100644
--- a/init/initramfs.c
+++ b/init/initramfs.c
@@ -188,14 +188,11 @@ static __initdata u32 hdr_csum;
 static void __init parse_header(char *s)
 {
 	unsigned long parsed[13];
-	char buf[9];
 	int i;
 
-	buf[8] = '\0';
-	for (i = 0, s += 6; i < 13; i++, s += 8) {
-		memcpy(buf, s, 8);
-		parsed[i] = simple_strtoul(buf, NULL, 16);
-	}
+	for (i = 0, s += 6; i < 13; i++, s += 8)
+		parsed[i] = simple_strntoul(s, NULL, 16, 8);
+
 	ino = parsed[0];
 	mode = parsed[1];
 	uid = parsed[2];
-- 
2.43.0