[PATCH v3] EDAC/mc_sysfs: refactor deprecated strncpy

[Justin Stitt]

`strncpy` is deprecated for use on NUL-terminated destination strings [1].

We should prefer more robust and less ambiguous string interfaces.

A suitable replacement is `strscpy` [2] due to the fact that it
guarantees NUL-termination on the destination buffer without needlessly
NUL-padding.

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
Link: https://github.com/KSPP/linux/issues/90
Cc: linux-hardening@xxxxxxxxxxxxxxx
Signed-off-by: Justin Stitt <justinstitt@xxxxxxxxxx>
---
Changes in v3:
- prefer strscpy to strscpy_pad (thanks Tony)
- Link to v2: https://lore.kernel.org/r/20230913-strncpy-drivers-edac-edac_mc_sysfs-c-v2-1-2d2e6bd43642@xxxxxxxxxx

Changes in v2:
- included refactor of another strncpy in same file
- Link to v1: https://lore.kernel.org/r/20230913-strncpy-drivers-edac-edac_mc_sysfs-c-v1-1-d232891b05b0@xxxxxxxxxx
---
Note: build-tested only.
---
 drivers/edac/edac_mc_sysfs.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/edac/edac_mc_sysfs.c b/drivers/edac/edac_mc_sysfs.c
index 15f63452a9be..9a5b4bbd8191 100644
--- a/drivers/edac/edac_mc_sysfs.c
+++ b/drivers/edac/edac_mc_sysfs.c
@@ -229,8 +229,7 @@ static ssize_t channel_dimm_label_store(struct device *dev,
 	if (copy_count == 0 || copy_count >= sizeof(rank->dimm->label))
 		return -EINVAL;
 
-	strncpy(rank->dimm->label, data, copy_count);
-	rank->dimm->label[copy_count] = '\0';
+	strscpy(rank->dimm->label, data, copy_count);
 
 	return count;
 }
@@ -535,7 +534,7 @@ static ssize_t dimmdev_label_store(struct device *dev,
 	if (copy_count == 0 || copy_count >= sizeof(dimm->label))
 		return -EINVAL;
 
-	strncpy(dimm->label, data, copy_count);
+	strscpy(dimm->label, data, copy_count);
 	dimm->label[copy_count] = '\0';
 
 	return count;

---
base-commit: 2dde18cd1d8fac735875f2e4987f11817cc0bc2c
change-id: 20230913-strncpy-drivers-edac-edac_mc_sysfs-c-e619b00124a3

Best regards,
--
Justin Stitt <justinstitt@xxxxxxxxxx>