2023-09-01 12:45:13

by Florian Westphal

[permalink] [raw]
Subject: Re: [PATCH nf v2] netfilter/osf: avoid OOB read

Wander Lairson Costa <[email protected]> wrote:
>
> diff --git a/net/netfilter/nfnetlink_osf.c b/net/netfilter/nfnetlink_osf.c
> index 8f1bfa6ccc2d..13fedf2aaa0f 100644
> --- a/net/netfilter/nfnetlink_osf.c
> +++ b/net/netfilter/nfnetlink_osf.c
> @@ -315,6 +315,9 @@ static int nfnl_osf_add_callback(struct sk_buff *skb,
>
> f = nla_data(osf_attrs[OSF_ATTR_FINGER]);
>
> + if (f->opt_num > ARRAY_SIZE(f->opt))
> + return -EINVAL;
> +

Hmm, this isn't enough; as far as I can see there is no validation
whatsover.

This should also check that all of:

char genre[MAXGENRELEN];
char version[MAXGENRELEN];
char subtype[MAXGENRELEN];

... have a NUL byte. You could use strnlen() == ARRAY_SIZE() -> EINVAL
for those.

Maybe there is more to be validated, I did not followup with all the
nested structures buried in user_finger struct.