[PATCH] netlink: fix NLMSG_DONE never enter family specific decoder

[Dmitry V. Levin]

On Sat, Jun 24, 2017 at 01:35:18PM +0800, JingPiao Chen wrote:
> * netlink.c (print_nlmsghdr): Remove condition
> nlmsghdr->nlmsg_type < NLMSG_MIN_TYPE.
> (decode_nlmsg_type): Add condition type >= NLMSG_MIN_TYPE.
> (decode_nlmsg_flags): Add condition type < NLMSG_MIN_TYPE.
> (decode_netlink_sock_diag): Add condition
> nlmsghdr->nlmsg_type < NLMSG_MIN_TYPE.
> ---
>  netlink.c           | 13 ++++++++-----
>  netlink_sock_diag.c |  3 +++
>  2 files changed, 11 insertions(+), 5 deletions(-)
> 
> diff --git a/netlink.c b/netlink.c
> index 87b389c..d990fad 100644
> --- a/netlink.c
> +++ b/netlink.c
> @@ -177,7 +177,7 @@ decode_nlmsg_type(const uint16_t type, const unsigned int family)
>  	const struct xlat *xlat = netlink_types;
>  	const char *dflt = "NLMSG_???";
>  
> -	if (family < ARRAY_SIZE(nlmsg_types)) {
> +	if (type >= NLMSG_MIN_TYPE && family < ARRAY_SIZE(nlmsg_types)) {
>  		if (nlmsg_types[family].decoder)
>  			decoder = nlmsg_types[family].decoder;
>  		if (nlmsg_types[family].xlat)
> @@ -194,6 +194,11 @@ decode_nlmsg_flags(const uint16_t flags, const uint16_t type, const int family)
>  {
>  	const struct xlat *table = NULL;
>  
> +	if (type < NLMSG_MIN_TYPE) {
> +		printflags(netlink_flags, flags, "NLM_F_???");
> +		return;
> +	}
> +

There is another printflags invocation in this function already,
can this duplication be avoided?

>  	switch (family) {
>  	case NETLINK_SOCK_DIAG:
>  		table = netlink_get_flags;
> @@ -246,10 +251,8 @@ print_nlmsghdr(struct tcb *tcp,
>  
>  	tprintf("{len=%u, type=", nlmsghdr->nlmsg_len);
>  
> -	const int hdr_family = (nlmsghdr->nlmsg_type < NLMSG_MIN_TYPE)
> -			       ? NL_FAMILY_DEFAULT
> -			       : (family != NL_FAMILY_DEFAULT
> -				  ? family : get_fd_nl_family(tcp, fd));
> +	const int hdr_family = family != NL_FAMILY_DEFAULT
> +			       ? family : get_fd_nl_family(tcp, fd);

Is the family needed for any nlmsg_type?  What about NLMSG_ERROR?


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