Messages in this thread | | | From | Wander Lairson Costa <> | Date | Thu, 31 Aug 2023 11:45:23 -0300 | Subject | Re: [PATCH nf v2] netfilter/osf: avoid OOB read |
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On Thu, Aug 31, 2023 at 10:37 AM Florian Westphal <fw@strlen.de> wrote: > > Wander Lairson Costa <wander@redhat.com> 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 > whatsoever. >
I didn't get it. It guarantees there is no OOB read of the opt array.
> 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. >
I think the correct way would be memchr(genre/version/subtype, 0, MAXGENRELEN).
> Maybe there is more to be validated. I did not followup with all the > nested structures buried in user_finger struct. >
I focused on the reported issue mainly because I am unfamiliar with the Netfilter layer. Let me take a deeper look.
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