strncpy() is deprecated for use on NUL-terminated destination strings [1] and as such we should prefer more robust and less ambiguous string interfaces. We expect ac->name to be NUL-terminated based on its usage with format strings: surface_charger.c: 190: ac->psy_desc.name = ac->name; ... power_supply_core.c: 174: dev_dbg(&psy->dev, "%s: Found supply : %s\n", 175: psy->desc->name, epsy->desc->name); Moreover, NUL-padding is not required as ac is already zero-allocated before being passed to spwr_ac_init(): surface_charger.c: 240: ac = devm_kzalloc(&sdev->dev, sizeof(*ac), GFP_KERNEL); 241: if (!ac) 242: return -ENOMEM; 243: 244: spwr_ac_init(ac, sdev, p->registry, p->name); ... this means any future NUL-byte assignments (like the ones that strncpy() does) are redundant. Considering the above, a suitable replacement is `strscpy` [2] due to the fact that it guarantees NUL-termination on the destination buffer without unnecessarily NUL-padding. Let's also opt for the more idiomatic strscpy() usage of: (dest, src, sizeof(dest)) 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> --- Note: build-tested only. Found with: $ rg "strncpy\(" --- drivers/power/supply/surface_charger.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/power/supply/surface_charger.c b/drivers/power/supply/surface_charger.c index cabdd8da12d0..7a6c62d6f883 100644 --- a/drivers/power/supply/surface_charger.c +++ b/drivers/power/supply/surface_charger.c @@ -175,7 +175,7 @@ static void spwr_ac_init(struct spwr_ac_device *ac, struct ssam_device *sdev, struct ssam_event_registry registry, const char *name) { mutex_init(&ac->lock); - strncpy(ac->name, name, ARRAY_SIZE(ac->name) - 1); + strscpy(ac->name, name, sizeof(ac->name)); ac->sdev = sdev; --- base-commit: bb55d7f7f7445abcc8db50e6a65d4315e79f75c7 change-id: 20231020-strncpy-drivers-power-supply-surface_charger-c-466920fb1f48 Best regards, -- Justin Stitt <justinstitt@xxxxxxxxxx>
