[PATCH 1/2] brcmfmac: add subtype check for event handling in data path

[Tyler Hicks]

From: Arend van Spriel <arend.vanspriel at broadcom.com>

For USB there is no separate channel being used to pass events
from firmware to the host driver and as such are passed over the
data path. In order to detect mock event messages an additional
check is needed on event subtype. This check is added conditionally
using unlikely() keyword.

Reviewed-by: Hante Meuleman <hante.meuleman at broadcom.com>
Reviewed-by: Pieter-Paul Giesberts <pieter-paul.giesberts at broadcom.com>
Reviewed-by: Franky Lin <franky.lin at broadcom.com>
Signed-off-by: Arend van Spriel <arend.vanspriel at broadcom.com>
Signed-off-by: Kalle Valo <kvalo at codeaurora.org>

CVE-2019-9503

(cherry picked from commit a4176ec356c73a46c07c181c6d04039fafa34a9f)
Signed-off-by: Tyler Hicks <tyhicks at canonical.com>
---
 drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c  |  5 +++--
 drivers/net/wireless/broadcom/brcm80211/brcmfmac/fweh.h  | 16 ++++++++++++----
 .../net/wireless/broadcom/brcm80211/brcmfmac/msgbuf.c    |  2 +-
 3 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c
index 860a4372cb56..09c5f67f4089 100644
--- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c
+++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c
@@ -464,7 +464,8 @@ void brcmf_rx_frame(struct device *dev, struct sk_buff *skb, bool handle_event)
 	} else {
 		/* Process special event packets */
 		if (handle_event)
-			brcmf_fweh_process_skb(ifp->drvr, skb);
+			brcmf_fweh_process_skb(ifp->drvr, skb,
+					       BCMILCP_SUBTYPE_VENDOR_LONG);
 
 		brcmf_netif_rx(ifp, skb);
 	}
@@ -481,7 +482,7 @@ void brcmf_rx_event(struct device *dev, struct sk_buff *skb)
 	if (brcmf_rx_hdrpull(drvr, skb, &ifp))
 		return;
 
-	brcmf_fweh_process_skb(ifp->drvr, skb);
+	brcmf_fweh_process_skb(ifp->drvr, skb, 0);
 	brcmu_pkt_buf_free_skb(skb);
 }
 
diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/fweh.h b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/fweh.h
index 816f80ea925b..ebd66fe0d949 100644
--- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/fweh.h
+++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/fweh.h
@@ -211,7 +211,7 @@ enum brcmf_fweh_event_code {
  */
 #define BRCM_OUI				"\x00\x10\x18"
 #define BCMILCP_BCM_SUBTYPE_EVENT		1
-
+#define BCMILCP_SUBTYPE_VENDOR_LONG		32769
 
 /**
  * struct brcm_ethhdr - broadcom specific ether header.
@@ -334,10 +334,10 @@ void brcmf_fweh_process_event(struct brcmf_pub *drvr,
 void brcmf_fweh_p2pdev_setup(struct brcmf_if *ifp, bool ongoing);
 
 static inline void brcmf_fweh_process_skb(struct brcmf_pub *drvr,
-					  struct sk_buff *skb)
+					  struct sk_buff *skb, u16 stype)
 {
 	struct brcmf_event *event_packet;
-	u16 usr_stype;
+	u16 subtype, usr_stype;
 
 	/* only process events when protocol matches */
 	if (skb->protocol != cpu_to_be16(ETH_P_LINK_CTL))
@@ -346,8 +346,16 @@ static inline void brcmf_fweh_process_skb(struct brcmf_pub *drvr,
 	if ((skb->len + ETH_HLEN) < sizeof(*event_packet))
 		return;
 
-	/* check for BRCM oui match */
 	event_packet = (struct brcmf_event *)skb_mac_header(skb);
+
+	/* check subtype if needed */
+	if (unlikely(stype)) {
+		subtype = get_unaligned_be16(&event_packet->hdr.subtype);
+		if (subtype != stype)
+			return;
+	}
+
+	/* check for BRCM oui match */
 	if (memcmp(BRCM_OUI, &event_packet->hdr.oui[0],
 		   sizeof(event_packet->hdr.oui)))
 		return;
diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/msgbuf.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/msgbuf.c
index 4e8397a0cbc8..ee922b052561 100644
--- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/msgbuf.c
+++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/msgbuf.c
@@ -1116,7 +1116,7 @@ static void brcmf_msgbuf_process_event(struct brcmf_msgbuf *msgbuf, void *buf)
 
 	skb->protocol = eth_type_trans(skb, ifp->ndev);
 
-	brcmf_fweh_process_skb(ifp->drvr, skb);
+	brcmf_fweh_process_skb(ifp->drvr, skb, 0);
 
 exit:
 	brcmu_pkt_buf_free_skb(skb);
-- 
2.7.4