Re: [PATCH net-next] net: metrics: add proper netlink validation

[Eric Dumazet <eric.dumazet@gmail.com>]

On 06/04/2018 04:46 PM, Eric Dumazet wrote:
> Before using nla_get_u32(), better make sure the attribute
> is of the proper size.
> 
> 

> Fixes: a919525ad832 ("net: Move fib_convert_metrics to metrics file")
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Reported-by: syzbot <syzkaller@googlegroups.com>
> Cc: David Ahern <dsahern@gmail.com>
> ---
>  net/ipv4/fib_semantics.c | 2 ++
>  net/ipv4/metrics.c       | 2 ++
>  2 files changed, 4 insertions(+)
> 
> diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
> index 6608db23f54b6afdac0455650b47d64b1b22b255..9a890be8a0265edb78da225a82e2cac120f2150f 100644
> --- a/net/ipv4/fib_semantics.c
> +++ b/net/ipv4/fib_semantics.c
> @@ -717,6 +717,8 @@ bool fib_metrics_match(struct fib_config *cfg, struct fib_info *fi)
>  			nla_strlcpy(tmp, nla, sizeof(tmp));
>  			val = tcp_ca_get_key_by_name(fi->fib_net, tmp, &ecn_ca);
>  		} else {
> +			if (nla_len(nla) != sizeof(u32)

Oh well, stupid typo.

> +				return false;
>  			val = nla_get_u32(nla);

I will send a V2.