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Message-ID: <b0a352781f58a829deadffbe2ef2085c97c6ab32.camel@perches.com>
Subject: Re: [PATCH] wifi: brcm80211: handle pmk_op allocation failure
From: Joe Perches <joe@perches.com>
To: Arend van Spriel <arend.vanspriel@broadcom.com>, Duoming Zhou
	 <duoming@zju.edu.cn>, linux-kernel@vger.kernel.org
Cc: brcm80211-dev-list.pdl@broadcom.com, brcm80211@lists.linux.dev, 
 linux-wireless@vger.kernel.org, justinstitt@google.com, john@keeping.me.uk,
  quic_alokad@quicinc.com, marcan@marcan.st, johannes.berg@intel.com, 
 linus.walleij@linaro.org, kvalo@kernel.org
Date: Tue, 27 Feb 2024 03:42:13 -0800
In-Reply-To: <87166784-79ab-4eb4-ad1e-af4bc31757b7@broadcom.com>
References: <20240227080613.34001-1-duoming@zju.edu.cn>
	 <87166784-79ab-4eb4-ad1e-af4bc31757b7@broadcom.com>
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On Tue, 2024-02-27 at 12:21 +0100, Arend van Spriel wrote:
> On 2/27/2024 9:06 AM, Duoming Zhou wrote:
> > The kzalloc() in brcmf_pmksa_v3_op() will return null if the
> > physical memory has run out. As a result, if we dereference
> > the null value, the null pointer dereference bug will happen.
> >=20
> > Return -ENOMEM from brcmf_pmksa_v3_op() if kzalloc() fails
> > for pmk_op.
>=20
> NAK (see below)
>=20
> Also this issue was reported earlier by Joe Perches. Not sure if he=20
> wants to be mentioned as such.

I think it's unimportant to be mentioned.

I think it's more important that the code be researched
that the simple return of -ENOMEM the appropriate fix
and is handled by all possible callers of the function.

>=20
> > Fixes: a96202acaea4 ("wifi: brcmfmac: cfg80211: Add support for PMKID_V=
3 operations")
> > Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
> > ---
> >   drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c | 5 +++++
> >   1 file changed, 5 insertions(+)
> >=20
> > diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.=
cq b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
> > index 28d6a30cc01..3b420b33188 100644
> > --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
> > +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
> > @@ -4322,6 +4322,10 @@ brcmf_pmksa_v3_op(struct brcmf_if *ifp, struct c=
fg80211_pmksa *pmksa,
> >   	int ret;
> >  =20
> >   	pmk_op =3D kzalloc(sizeof(*pmk_op), GFP_KERNEL);
> > +	if (!pmk_op) {
> > +		ret =3D -ENOMEM;
> > +		goto out;
> > +	}
>=20
> There is really no need to introduce a new label for this. Although you=
=20
> can kfree() a NULL pointer there is no need to do so when you know=20
> already it is NULL. Just return -ENOMEM and be done with it.
>=20
> Regards,
> Arend
>=20
> >   	pmk_op->version =3D cpu_to_le16(BRCMF_PMKSA_VER_3);
> >  =20
> >   	if (!pmksa) {
> > @@ -4340,6 +4344,7 @@ brcmf_pmksa_v3_op(struct brcmf_if *ifp, struct cf=
g80211_pmksa *pmksa,
> >   	pmk_op->length =3D cpu_to_le16(length);
> >  =20
> >   	ret =3D brcmf_fil_iovar_data_set(ifp, "pmkid_info", pmk_op, sizeof(*=
pmk_op));
> > +out:
> >   	kfree(pmk_op);
> >   	return ret;
> >   }