Re: [PATCH 4/4] lwip: Fix a buffer overflow and clear compiler warnings

[Samuel Thibault]

Joan Lledó, le sam. 11 août 2018 18:17:10 +0200, a ecrit:
> GCC 8 new warning -Wstringop-truncation detected some buffer overflows.
> 
> * lwip/options.c (parse_opt): Fix the buffer overflow.
> * lwip/pfinet-ops.c (dev_ifconf): Likewise.
> ---
>  lwip/options.c    | 2 +-
>  lwip/pfinet-ops.c | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/lwip/options.c b/lwip/options.c
> index 6591ac52..d35b9f32 100644
> --- a/lwip/options.c
> +++ b/lwip/options.c
> @@ -133,7 +133,7 @@ parse_opt (int opt, char *arg, struct argp_state *state)
>       }
>        in = h->curint;
>  
> -      strncpy (in->dev_name, arg, DEV_NAME_LEN);
> +      strncpy (in->dev_name, arg, sizeof(in->dev_name)-1);

Mmm, but if arg is longer than the given size and doesn't contain a \0,
in->dev_name will not contain one either?

>        break;
>  
>      case 'a':
> diff --git a/lwip/pfinet-ops.c b/lwip/pfinet-ops.c
> index 56b7dcd1..1af2a3fe 100644
> --- a/lwip/pfinet-ops.c
> +++ b/lwip/pfinet-ops.c
> @@ -61,7 +61,7 @@ dev_ifconf (struct ifconf *ifc)
>         memset (ifr, 0, sizeof (struct ifreq));
>  
>         strncpy (ifr->ifr_name, netif_get_state (netif)->devname,
> -                strlen (netif_get_state (netif)->devname) + 1);
> +                sizeof (ifr->ifr_name)-1);

Similarly.

Samuel