On Thu, 27 Jul 2023 23:53:24 +0200, 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`! > > It should be noted that, in this case, the destination buffer has a > length strictly greater than the source string. Moreover, the source > string is NUL-terminated (and so is the destination) which means there > was no real bug happening here. Nonetheless, this patch would get us one > step closer to eliminating the `strncpy` API in the kernel, as its use > is too ambiguous. We need to favor less ambiguous replacements such as: > strscpy, strscpy_pad, strtomem and strtomem_pad (amongst others). > > Technically, my patch yields subtly different behavior. The original > implementation with `strncpy` would fill the entire destination buffer > with null bytes [3] while `strscpy` will leave the junk, uninitialized > bytes trailing after the _mandatory_ NUL-termination. So, if somehow > `pcm->name` or `card->driver/shortname/longname` require this > NUL-padding behavior then `strscpy_pad` should be used. My > interpretation, though, is that the aforementioned fields are just fine > as NUL-terminated strings. Please correct my assumptions if needed and > I'll send in a v2. > > [1]: www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings > [2]: manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html > [3]: https://linux.die.net/man/3/strncpy > > Link: https://github.com/KSPP/linux/issues/90 > Signed-off-by: Justin Stitt <justinstitt@xxxxxxxxxx> Applied now. Thanks. Takashi
