From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lorenzo Bianconi Date: Sat, 04 May 2019 09:52:16 +0000 Subject: Re: [PATCH] mt76: mt7615: Use after free in mt7615_mcu_set_bcn() Message-Id: <20190504095215.GA23263@localhost.localdomain> MIME-Version: 1 Content-Type: multipart/mixed; boundary="PNTmBPCT7hxwcZjr" List-Id: References: <20190503130909.GI29695@mwanda> In-Reply-To: <20190503130909.GI29695@mwanda> To: Dan Carpenter Cc: Felix Fietkau , Ryder Lee , Lorenzo Bianconi , Roy Luo , Kalle Valo , Matthias Brugger , linux-wireless-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mediatek-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, kernel-janitors-u79uwXL29TY76Z2rM5mHXA@public.gmane.org --PNTmBPCT7hxwcZjr Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Acked-by: Lorenzo Bianconi > We dereference "skb" when we assign: >=20 > req.pkt_len =3D cpu_to_le16(MT_TXD_SIZE + skb->len); > ^^^^^^^^ > So this patch just moves the dev_kfree_skb() down a bit to avoid the > use after free. >=20 > Fixes: 04b8e65922f6 ("mt76: add mac80211 driver for MT7615 PCIe-based chi= psets") > Signed-off-by: Dan Carpenter > --- > drivers/net/wireless/mediatek/mt76/mt7615/mcu.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) >=20 > diff --git a/drivers/net/wireless/mediatek/mt76/mt7615/mcu.c b/drivers/ne= t/wireless/mediatek/mt76/mt7615/mcu.c > index ea67c6022fe6..dc1301effa24 100644 > --- a/drivers/net/wireless/mediatek/mt76/mt7615/mcu.c > +++ b/drivers/net/wireless/mediatek/mt76/mt7615/mcu.c > @@ -1270,7 +1270,6 @@ int mt7615_mcu_set_bcn(struct mt7615_dev *dev, stru= ct ieee80211_vif *vif, > mt7615_mac_write_txwi(dev, (__le32 *)(req.pkt), skb, wcid, NULL, > 0, NULL); > memcpy(req.pkt + MT_TXD_SIZE, skb->data, skb->len); > - dev_kfree_skb(skb); > =20 > req.omac_idx =3D mvif->omac_idx; > req.enable =3D en; > @@ -1281,6 +1280,7 @@ int mt7615_mcu_set_bcn(struct mt7615_dev *dev, stru= ct ieee80211_vif *vif, > req.pkt_len =3D cpu_to_le16(MT_TXD_SIZE + skb->len); > req.tim_ie_pos =3D cpu_to_le16(MT_TXD_SIZE + tim_off); > =20 > + dev_kfree_skb(skb); > skb =3D mt7615_mcu_msg_alloc(&req, sizeof(req)); > =20 > return mt7615_mcu_msg_send(dev, skb, MCU_EXT_CMD_BCN_OFFLOAD, > --=20 > 2.18.0 >=20 --PNTmBPCT7hxwcZjr Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQTquNwa3Txd3rGGn7Y6cBh0uS2trAUCXM1gzAAKCRA6cBh0uS2t rDeKAQDGjECddgKPoW1n3Dnye8aHew95bCQqgsIeRCLiVSH00QD/VWP4FLjdbVHM +9OT95BeBDbj0eG7VaB6OROPr+8wLwg= =UKNW -----END PGP SIGNATURE----- --PNTmBPCT7hxwcZjr--