On Thu, Jul 27, 2023 at 10:46:13PM +0000, Justin Stitt wrote:
`strncpy` is deprecated for use on NUL-terminated destination strings [1].
A suitable replacement is `strscpy` [2] due to the fact that it guarantees NUL-termination on its destination buffer argument which is _not_ always the case for `strncpy`!
In this case, though, there was care taken to ensure that the destination buffer would be NUL-terminated. The destination buffer is zero-initialized and each `pm860x->name[i]` has a size of `MAX_NAME_LENGTH + 1`. This means that there is unlikely to be a bug here.
However, in an attempt to eliminate the usage of the `strncpy` API as well as disambiguate implementations, replacements such as: `strscpy`, `strscpy_pad`, `strtomem` and `strtomem_pad` should be preferred.
We are able to eliminate the need for `len + 1` since `strscpy` guarantees NUL-termination for its destination buffer as per its implementation [3]:
| /* Hit buffer length without finding a NUL; force NUL-termination. */ | if (res) | dest[res-1] = '\0';
Link: https://github.com/KSPP/linux/issues/90 Signed-off-by: Justin Stitt justinstitt@google.com
sound/soc/codecs/88pm860x-codec.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/sound/soc/codecs/88pm860x-codec.c b/sound/soc/codecs/88pm860x-codec.c index 3574c68e0dda..d99b674d574b 100644 --- a/sound/soc/codecs/88pm860x-codec.c +++ b/sound/soc/codecs/88pm860x-codec.c @@ -143,7 +143,7 @@ struct pm860x_priv { struct pm860x_det det;
int irq[4];
- unsigned char name[4][MAX_NAME_LEN+1];
- unsigned char name[4][MAX_NAME_LEN];
};
/* -9450dB to 0dB in 150dB steps ( mute instead of -9450dB) */ @@ -1373,7 +1373,7 @@ static int pm860x_codec_probe(struct platform_device *pdev) return -EINVAL; } pm860x->irq[i] = res->start + chip->irq_base;
strncpy(pm860x->name[i], res->name, MAX_NAME_LEN);
strscpy(pm860x->name[i], res->name, MAX_NAME_LEN);
res->name is (perhaps) unbounded in length:
struct resource { ... const char *name; ... };
So reducing struct pm860x_priv::name's size _might_ have a user-visible effect, but probably not.
Reviewed-by: Kees Cook keescook@chromium.org
-Kees