`strncpy` is deprecated for use on NUL-terminated destination strings [1]. Let's refactor this kcalloc() + strncpy() into a kmemdup_nul() which has more obvious behavior and is less error prone.
To avoid truncating the last byte supply `...length + 1` to kmemdup_nul() as `element->string.length` does not account for the trailing null as made obvious from it's definition (and associated comment): | u32 length; /* # of bytes in string, excluding trailing null */ ... this is precisely what the original kcalloc invocation did as well. Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1] Link: https://github.com/KSPP/linux/issues/90 Cc: linux-hardening@vger.kernel.org Signed-off-by: Justin Stitt <justinst...@google.com> --- Changes in v3: - refactor to use kmemdup_nul() (thanks Thomas and Kees) - change commit msg to reflect ^ - rebase onto 2cf0f71562387282 - Link to v2: https://lore.kernel.org/r/20230919-strncpy-drivers-hwmon-acpi_power_meter-c-v2-1-8348432d6...@google.com Changes in v2: - use memcpy over strscpy (thanks Kees) - Link to v1: https://lore.kernel.org/r/20230914-strncpy-drivers-hwmon-acpi_power_meter-c-v1-1-905297479...@google.com --- drivers/hwmon/acpi_power_meter.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/drivers/hwmon/acpi_power_meter.c b/drivers/hwmon/acpi_power_meter.c index fa28d447f0df..146c4f09c897 100644 --- a/drivers/hwmon/acpi_power_meter.c +++ b/drivers/hwmon/acpi_power_meter.c @@ -796,14 +796,13 @@ static int read_capabilities(struct acpi_power_meter_resource *resource) goto error; } - *str = kcalloc(element->string.length + 1, sizeof(u8), - GFP_KERNEL); + *str = kmemdup_nul(element->string.pointer, element->string.length + 1, + GFP_KERNEL); if (!*str) { res = -ENOMEM; goto error; } - strncpy(*str, element->string.pointer, element->string.length); str++; } --- base-commit: 2cf0f715623872823a72e451243bbf555d10d032 change-id: 20230914-strncpy-drivers-hwmon-acpi_power_meter-c-c9f2d8053bef Best regards, -- Justin Stitt <justinst...@google.com>
