| Message ID | 20230727-asoc-intel-skylake-remove-deprecated-strncpy-v2-1-152830093921@google.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] ASoC: Intel: Skylake: replace deprecated strncpy with strscpy | expand |
On Thu, Jul 27, 2023 at 08:30:18PM +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_ the case for `strncpy`! > > It was pretty difficult, in this case, to try and figure out whether or > not the destination buffer was zero-initialized. If it is and this > behavior is relied on then perhaps `strscpy_pad` is the preferred > option here. > > Kees was able to help me out and identify the following code snippet > which seems to show that the destination buffer is zero-initialized. > > | skl = devm_kzalloc(&pci->dev, sizeof(*skl), GFP_KERNEL); > > With this information, I opted for `strscpy` since padding is seemingly > not required. > > [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 > > Link: https://github.com/KSPP/linux/issues/90 > Suggested-by: Kees Cook <keescook@chromium.org> > Signed-off-by: Justin Stitt <justinstitt@google.com> Thanks for the updates! And based on the details from Amadeusz, it looks safe. Reviewed-by: Kees Cook <keescook@chromium.org>
diff --git a/sound/soc/intel/skylake/skl-topology.c b/sound/soc/intel/skylake/skl-topology.c index 96cfebded072..0ead3ea605cd 100644 --- a/sound/soc/intel/skylake/skl-topology.c +++ b/sound/soc/intel/skylake/skl-topology.c @@ -3159,7 +3159,7 @@ static int skl_tplg_fill_str_mfest_tkn(struct device *dev, return -EINVAL; } - strncpy(skl->lib_info[ref_count].name, + strscpy(skl->lib_info[ref_count].name, str_elem->string, ARRAY_SIZE(skl->lib_info[ref_count].name)); ref_count++;
`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_ the case for `strncpy`! It was pretty difficult, in this case, to try and figure out whether or not the destination buffer was zero-initialized. If it is and this behavior is relied on then perhaps `strscpy_pad` is the preferred option here. Kees was able to help me out and identify the following code snippet which seems to show that the destination buffer is zero-initialized. | skl = devm_kzalloc(&pci->dev, sizeof(*skl), GFP_KERNEL); With this information, I opted for `strscpy` since padding is seemingly not required. [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 Link: https://github.com/KSPP/linux/issues/90 Suggested-by: Kees Cook <keescook@chromium.org> Signed-off-by: Justin Stitt <justinstitt@google.com> --- Changes in v2: - Remove extraneous logic change (thanks Kees) - Link to v1: https://lore.kernel.org/r/20230726-asoc-intel-skylake-remove-deprecated-strncpy-v1-1-020e04184c7d@google.com --- sound/soc/intel/skylake/skl-topology.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- base-commit: 0b4a9fdc9317440a71d4d4c264a5650bf4a90f3c change-id: 20230726-asoc-intel-skylake-remove-deprecated-strncpy-9dbcfc26040c Best regards, -- Justin Stitt <justinstitt@google.com>