On Tue, Jul 25, 2023 at 10:08:38PM +0000, justinstitt@google.com 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].
^^^^ 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@google.com
But otherwise, looks good:
Reviewed-by: Kees Cook keescook@chromium.org
-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);
strncpy((char *)route->sink, buf, len);
strscpy((char *)route->sink, buf, len);
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@google.com