[PATCH v2] partitions/ibm: refactor deprecated strncpy

[Justin Stitt <justinstitt@google.com>]

`strncpy` is deprecated [1] and we should favor different interfaces.

A suitable replacement is `strtomem_pad` as it is a more robust and less
ambiguous interface. In this case, the destination buffer is not
necessarily NUL-terminated as Heiko points out [2]. Using `strtomem_pad`
over strncpy means it is now more obvious what is expected of the
destination buffer: 1) Not necessarily NUL-terminated and 2) padded with
NUL-bytes

Link: www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings[1]
Link: https://lore.kernel.org/all/20230823134936.14378-E-hca@linux.ibm.com/ [2]
Link: https://github.com/KSPP/linux/issues/90
Suggested-by: Kees Cook <keescook@chromium.org>
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Justin Stitt <justinstitt@google.com>
---
Changes in v2:
- prefer `strtomem_pad` over `strscpy` (thanks Kees)
- Link to v1: https://lore.kernel.org/r/20230822-strncpy-block-partitions-cmdline-ibm-v1-1-154dea8f755c@google.com
---
 block/partitions/ibm.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/block/partitions/ibm.c b/block/partitions/ibm.c
index 403756dbd50d..56c076c5523d 100644
--- a/block/partitions/ibm.c
+++ b/block/partitions/ibm.c
@@ -111,11 +111,11 @@ static int find_label(struct parsed_partitions *state,
 		    !strcmp(temp, "LNX1") ||
 		    !strcmp(temp, "CMS1")) {
 			if (!strcmp(temp, "VOL1")) {
-				strncpy(type, label->vol.vollbl, 4);
-				strncpy(name, label->vol.volid, 6);
+				strtomem_pad(type, label->vol.vollbl, 4);
+				strtomem_pad(name, label->vol.volid, 6);
 			} else {
-				strncpy(type, label->lnx.vollbl, 4);
-				strncpy(name, label->lnx.volid, 6);
+				strtomem_pad(type, label->lnx.vollbl, 4);
+				strtomem_pad(name, label->lnx.volid, 6);
 			}
 			EBCASC(type, 4);
 			EBCASC(name, 6);

---
base-commit: 706a741595047797872e669b3101429ab8d378ef
change-id: 20230822-strncpy-block-partitions-cmdline-ibm-7f5bcca507ea

Best regards,
--
Justin Stitt <justinstitt@google.com>