On Tue, Jul 25, 2023 at 10:08:38PM +0000, justinstitt@xxxxxxxxxx wrote: > `strncpy` is deprecated for use on NUL-terminated destination strings > [1]. > > A suitable replacement is `strscpy` [2]. For future patches like this, can you include the rationale for _why_ strscpy() is suitable? (i.e. how did you check that it doesn't need zero-padding, the dest is expected to always be NUL-terminated, etc.) I had fun looking through this code -- it's a bit of a maze! I can see in the initializer for "route" (soc_tplg_dapm_graph_elems_load()), that all the strings pointed at from "elem" are being checked for NUL-termination. That this code is doing an in-place rewrite of the string is pretty unusual (i.e. specifically casting around the "const"), but it looks quite intentional. :) > There are some hopes that someday the `strncpy` api could be ripped out This can be rephrased, perhaps, as: There is a goal to eliminate the `strncpy` API in the kernel, as its use is too ambiguous, instead moving to the unambiguous replacements (strscpy, strscpy_pad, strtomem, strtomem_pad, strlcpy) [1]. > due to the vast number of suitable replacements (strscpy, strscpy_pad, > strtomem, strtomem_pad, strlcpy) [1]. > > [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 > > --- ^^^^ this triple-dash is going to cause some tooling to lose your S-o-b, as it indicates the end of the commit log. > > > Link: https://github.com/KSPP/linux/issues/90 > Signed-off-by: Justin Stitt <justinstitt@xxxxxxxxxx> But otherwise, looks good: Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx> -Kees > --- > sound/soc/intel/avs/topology.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/sound/soc/intel/avs/topology.c b/sound/soc/intel/avs/topology.c > index cdb4ec500261..45d0eb2a8e71 100644 > --- a/sound/soc/intel/avs/topology.c > +++ b/sound/soc/intel/avs/topology.c > @@ -1388,12 +1388,12 @@ static int avs_route_load(struct snd_soc_component *comp, int index, > port = __ffs(mach->mach_params.i2s_link_mask); > > snprintf(buf, len, route->source, port); > - strncpy((char *)route->source, buf, len); > + strscpy((char *)route->source, buf, len); > snprintf(buf, len, route->sink, port); > - strncpy((char *)route->sink, buf, len); > + strscpy((char *)route->sink, buf, len); > if (route->control) { > snprintf(buf, len, route->control, port); > - strncpy((char *)route->control, buf, len); > + strscpy((char *)route->control, buf, len); > } > } > > > --- > base-commit: 0b4a9fdc9317440a71d4d4c264a5650bf4a90f3c > change-id: 20230725-sound-soc-intel-avs-remove-deprecated-strncpy-2bc41a5a5f81 > > Best regards, > -- > Justin Stitt <justinstitt@xxxxxxxxxx> > -- Kees Cook
