netdev - Re: [PATCH net] mac80211_hwsim: fix potential NULL deref in hwsim_pmsr_report

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Message-ID: <CANn89i+5R2B00zkjocOOSWRLB0ZNBgjdMLSBbUFpcTOH=9obAw@mail.gmail.com>
Date:   Tue, 4 Apr 2023 19:01:15 +0200
From:   Eric Dumazet <edumazet@...gle.com>
To:     Simon Horman <simon.horman@...igine.com>
Cc:     "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Johannes Berg <johannes@...solutions.net>,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        eric.dumazet@...il.com, syzbot <syzkaller@...glegroups.com>,
        Jaewan Kim <jaewan@...gle.com>,
        Johannes Berg <johannes.berg@...el.com>
Subject: Re: [PATCH net] mac80211_hwsim: fix potential NULL deref in hwsim_pmsr_report_nl()

On Tue, Apr 4, 2023 at 6:18 PM Simon Horman <simon.horman@...igine.com> wrote:
>
> On Tue, Apr 04, 2023 at 01:48:03PM +0000, Eric Dumazet wrote:
> > syzbot reported a NULL deref caused by a missing check
> > in hwsim_pmsr_report_nl(), and bisected the issue to cited commit.
> >
>
> Hi Eric,
>
> I think this is for net-next / wireless-next as
> the above mentioned patch does not seem to be in Linus's tree.

Oh right, script error on my side. This was generated from -next tree.

>
> > ---
> >  drivers/net/wireless/virtual/mac80211_hwsim.c | 2 ++
> >  1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/net/wireless/virtual/mac80211_hwsim.c b/drivers/net/wireless/virtual/mac80211_hwsim.c
> > index f446d8f6e1f6e1df108db00e898fa02970162585..701e14b8e6fe0cae7ee2478c8dff0f2327b54a70 100644
> > --- a/drivers/net/wireless/virtual/mac80211_hwsim.c
> > +++ b/drivers/net/wireless/virtual/mac80211_hwsim.c
> > @@ -3761,6 +3761,8 @@ static int hwsim_pmsr_report_nl(struct sk_buff *msg, struct genl_info *info)
> >       int rem;
> >
> >       src = nla_data(info->attrs[HWSIM_ATTR_ADDR_TRANSMITTER]);
> > +     if (!src)
> > +             return -EINVAL;
> >       data = get_hwsim_data_ref_from_addr(src);
> >       if (!data)
> >               return -EINVAL;
>
> I could well be wrong, but this looks a little odd given that nla_data is:
>
> static inline void *nla_data(const struct nlattr *nla)
> {
>         return (char *) nla + NLA_HDRLEN;
> }
>
> Perhaps we want something like this (*compile tested only!*) ?
>
>         if (!info->attrs[HWSIM_ATTR_ADDR_TRANSMITTER])
>                 return -EINVAL;
>         src = nla_data(info->attrs[HWSIM_ATTR_ADDR_TRANSMITTER]);

Oh right, thanks for reviewing this :)

I will send a V2 soon.