netdev - Re: [PATCH net-next] netlink: make getters tolerate NULL nla arg

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Message-ID: <87eevzsa2m.fsf@toke.dk>
Date:   Thu, 16 Jan 2020 16:19:29 +0100
From:   Toke Høiland-Jørgensen <toke@...hat.com>
To:     Florian Westphal <fw@...len.de>, netdev@...r.kernel.org
Cc:     Florian Westphal <fw@...len.de>
Subject: Re: [PATCH net-next] netlink: make getters tolerate NULL nla arg

Florian Westphal <fw@...len.de> writes:

> One recurring bug pattern triggered by syzbot is NULL dereference in
> netlink code paths due to a missing "tb[NL_ARG_FOO] != NULL" test.
>
> At least some of these missing checks would not have crashed the kernel if
> the various nla_get_XXX helpers would return 0 in case of missing arg.

Won't this risk just papering over the issue and lead to subtly wrong
behaviour instead? At least a crash is somewhat visible :)

-Toke