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 priv->firmware_id to be NUL-terminated based on its usage
with seq_printf() and strlen() in atmel.c:
1420 | seq_printf(m, "%s loaded by host\n", priv->firmware_id);
...
3884 | if (strlen(priv->firmware_id) == 0) {
NUL-padding is not required, which is evident by the usage of a plain
strcpy():
3891 | strcpy(priv->firmware_id, "atmel_at76c502.bin");
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 replace hard-coded lengths to be `sizeof(...)` for buffers
that the compiler can detect the size for as this is less error prone.
Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strcpy [2]
Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [3]
Link: https://github.com/KSPP/linux/issues/90
Cc: linux-hardening@xxxxxxxxxxxxxxx
Signed-off-by: Justin Stitt <justinstitt@xxxxxxxxxx>
---
Changes in v2:
- leave strcpy() usage as is (thanks Kees)
- Link to v1: https://lore.kernel.org/r/20231016-strncpy-drivers-net-wireless-atmel-atmel-c-v1-1-038d0e73c402@xxxxxxxxxx
---
Note: build-tested only.
Found with: $ rg "strncpy\("
---
drivers/net/wireless/atmel/atmel.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/drivers/net/wireless/atmel/atmel.c b/drivers/net/wireless/atmel/atmel.c
index 7c2d1c588156..99920430e8b4 100644
--- a/drivers/net/wireless/atmel/atmel.c
+++ b/drivers/net/wireless/atmel/atmel.c
@@ -2651,8 +2651,7 @@ static int atmel_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
priv->firmware = new_firmware;
priv->firmware_length = com.len;
- strncpy(priv->firmware_id, com.id, 31);
- priv->firmware_id[31] = '\0';
+ strscpy(priv->firmware_id, com.id, sizeof(priv->firmware_id));
break;
case ATMELRD:
---
base-commit: cbf3a2cb156a2c911d8f38d8247814b4c07f49a2
change-id: 20231016-strncpy-drivers-net-wireless-atmel-atmel-c-7ca951cf7cfa
Best regards,
--
Justin Stitt <justinstitt@xxxxxxxxxx>
