On Wed, Oct 11, 2023 at 09:48:39PM +0000, Justin Stitt wrote:
> strncpy() is deprecated for use on NUL-terminated destination strings
> [1] and as such we should prefer more robust and less ambiguous string
> interfaces.
>
> We expect res->name to be NUL-terminated based on its usage with format
> strings:
> | dev_err(cpp->dev.parent, "Dangling area:
> %d:%d:%d:0x%0llx-0x%0llx%s%s\n",
> | NFP_CPP_ID_TARGET_of(res->cpp_id),
> | NFP_CPP_ID_ACTION_of(res->cpp_id),
> | NFP_CPP_ID_TOKEN_of(res->cpp_id),
> | res->start, res->end,
> | res->name ? " " : "",
> | res->name ? res->name : "");
> ... and with strcmp()
> | if (!strcmp(res->name, NFP_RESOURCE_TBL_NAME)) {
>
> Moreover, NUL-padding is not required as `res` is already
> zero-allocated:
> | res = kzalloc(sizeof(*res), GFP_KERNEL);
>
> Considering the above, a suitable replacement is `strscpy` [2] due to
> the fact that it guarantees NUL-termination on the destination buffer
> without unnecessarily NUL-padding.
>
> Let's also opt to use the more idiomatic strscpy() usage of (dest, src,
> sizeof(dest)) rather than (dest, src, SOME_LEN).
>
> Typically the pattern of 1) allocate memory for string, 2) copy string
> into freshly-allocated memory is a candidate for kmemdup_nul() but in
> this case we are allocating the entirety of the `res` struct and that
> should stay as is. As mentioned above, simple 1:1 replacement of strncpy
> -> strscpy :)
>
> Link:
> https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings
> [1]
> Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html
> [2]
> Link: https://github.com/KSPP/linux/issues/90
> Cc: [email protected]
> Signed-off-by: Justin Stitt <[email protected]>
> ---
> Note: build-tested only.
>
> Found with: $ rg "strncpy\("
Thanks Justin, I did also now check it on a nfp.
Acked-by: Louis Peens <[email protected]>
> ---
> drivers/net/ethernet/netronome/nfp/nfpcore/nfp_resource.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_resource.c
> b/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_resource.c
> index ce7492a6a98f..279ea0b56955 100644
> --- a/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_resource.c
> +++ b/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_resource.c
> @@ -159,7 +159,7 @@ nfp_resource_acquire(struct nfp_cpp *cpp, const char
> *name)
> if (!res)
> return ERR_PTR(-ENOMEM);
>
> - strncpy(res->name, name, NFP_RESOURCE_ENTRY_NAME_SZ);
> + strscpy(res->name, name, sizeof(res->name));
>
> dev_mutex = nfp_cpp_mutex_alloc(cpp, NFP_RESOURCE_TBL_TARGET,
> NFP_RESOURCE_TBL_BASE,
>
> ---
> base-commit: cbf3a2cb156a2c911d8f38d8247814b4c07f49a2
> change-id:
> 20231011-strncpy-drivers-net-ethernet-netronome-nfp-nfpcore-nfp_resource-c-1812b8357fcd
>
> Best regards,
> --
> Justin Stitt <[email protected]>
>
