[dpdk-dev] [PATCH v2 06/18] drivers/net/nfp/nfpcore: fix off-by-one and no NUL on strncpy use

[Alejandro Lucero]

On Wed, May 9, 2018 at 2:31 AM, Andy Green <andy at warmcat.com> wrote:

> /home/agreen/projects/dpdk/drivers/net/nfp/nfpcore/nfp_resource.c:
> 76:2:error: ‘strncpy’ output may be truncated copying 8 bytes from
> a string of length 8 [-Werror=stringop-truncation]
>   strncpy(name_pad, res->name, sizeof(name_pad));
>
> Signed-off-by: Andy Green <andy at warmcat.com>
> ---
>  drivers/net/nfp/nfpcore/nfp_resource.c |    8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/nfp/nfpcore/nfp_resource.c
> b/drivers/net/nfp/nfpcore/nfp_resource.c
> index e1df2b2e1..a165b93df 100644
> --- a/drivers/net/nfp/nfpcore/nfp_resource.c
> +++ b/drivers/net/nfp/nfpcore/nfp_resource.c
> @@ -7,6 +7,8 @@
>  #include <time.h>
>  #include <endian.h>
>
> +#include <rte_string_fns.h>
> +
>  #include "nfp_cpp.h"
>  #include "nfp6000/nfp6000.h"
>  #include "nfp_resource.h"
> @@ -65,15 +67,15 @@ struct nfp_resource {
>  static int
>  nfp_cpp_resource_find(struct nfp_cpp *cpp, struct nfp_resource *res)
>  {
> -       char name_pad[NFP_RESOURCE_ENTRY_NAME_SZ] = {};
> +       char name_pad[NFP_RESOURCE_ENTRY_NAME_SZ + 2];
>         struct nfp_resource_entry entry;
>         uint32_t cpp_id, key;
>         int ret, i;
>
>         cpp_id = NFP_CPP_ID(NFP_RESOURCE_TBL_TARGET, 3, 0);  /* Atomic
> read */
>
> -       memset(name_pad, 0, NFP_RESOURCE_ENTRY_NAME_SZ);
> -       strncpy(name_pad, res->name, sizeof(name_pad));
> +       memset(name_pad, 0, sizeof(name_pad));
> +       strlcpy(name_pad, res->name, sizeof(name_pad));
>
>         /* Search for a matching entry */
>         if (!memcmp(name_pad, NFP_RESOURCE_TBL_NAME "\0\0\0\0\0\0\0\0",
> 8)) {
>
>
I'm afraid this patch is breaking the PMD NFP initialization. It is due to
how the name pad is used for getting a key which is compared against a key
generated by the firmware.

Because the name_pad size change, this next change is also required:

-       key = nfp_crc32_posix(name_pad, sizeof(name_pad));

+       key = nfp_crc32_posix(name_pad, NFP_RESOURCE_ENTRY_NAME_SZ);