[PATCH v3] wifi: mwifiex: Fix oob check condition in mwifiex_process_rx_packet

[Pin-yen Lin <treapking@chromium.org>]

Only skip the code path trying to access the rfc1042 headers when the
buffer is too small, so the driver can still process packets without
rfc1042 headers.

Fixes: 119585281617 ("wifi: mwifiex: Fix OOB and integer underflow when rx packets")
Signed-off-by: Pin-yen Lin <treapking@chromium.org>

---

Changes in v3:
- Really apply the sizeof call fix as it was missed in the previous patch

Changes in v2:
- Fix sizeof call (sizeof(rx_pkt_hdr) --> sizeof(*rx_pkt_hdr))

 drivers/net/wireless/marvell/mwifiex/sta_rx.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/drivers/net/wireless/marvell/mwifiex/sta_rx.c b/drivers/net/wireless/marvell/mwifiex/sta_rx.c
index 65420ad67416..257737137cd7 100644
--- a/drivers/net/wireless/marvell/mwifiex/sta_rx.c
+++ b/drivers/net/wireless/marvell/mwifiex/sta_rx.c
@@ -86,7 +86,8 @@ int mwifiex_process_rx_packet(struct mwifiex_private *priv,
 	rx_pkt_len = le16_to_cpu(local_rx_pd->rx_pkt_length);
 	rx_pkt_hdr = (void *)local_rx_pd + rx_pkt_off;
 
-	if (sizeof(*rx_pkt_hdr) + rx_pkt_off > skb->len) {
+	if (sizeof(rx_pkt_hdr->eth803_hdr) + sizeof(rfc1042_header) +
+	    rx_pkt_off > skb->len) {
 		mwifiex_dbg(priv->adapter, ERROR,
 			    "wrong rx packet offset: len=%d, rx_pkt_off=%d\n",
 			    skb->len, rx_pkt_off);
@@ -95,12 +96,13 @@ int mwifiex_process_rx_packet(struct mwifiex_private *priv,
 		return -1;
 	}
 
-	if ((!memcmp(&rx_pkt_hdr->rfc1042_hdr, bridge_tunnel_header,
-		     sizeof(bridge_tunnel_header))) ||
-	    (!memcmp(&rx_pkt_hdr->rfc1042_hdr, rfc1042_header,
-		     sizeof(rfc1042_header)) &&
-	     ntohs(rx_pkt_hdr->rfc1042_hdr.snap_type) != ETH_P_AARP &&
-	     ntohs(rx_pkt_hdr->rfc1042_hdr.snap_type) != ETH_P_IPX)) {
+	if (sizeof(*rx_pkt_hdr) + rx_pkt_off <= skb->len &&
+	    ((!memcmp(&rx_pkt_hdr->rfc1042_hdr, bridge_tunnel_header,
+		      sizeof(bridge_tunnel_header))) ||
+	     (!memcmp(&rx_pkt_hdr->rfc1042_hdr, rfc1042_header,
+		      sizeof(rfc1042_header)) &&
+	      ntohs(rx_pkt_hdr->rfc1042_hdr.snap_type) != ETH_P_AARP &&
+	      ntohs(rx_pkt_hdr->rfc1042_hdr.snap_type) != ETH_P_IPX))) {
 		/*
 		 *  Replace the 803 header and rfc1042 header (llc/snap) with an
 		 *    EthernetII header, keep the src/dst and snap_type
-- 
2.42.0.283.g2d96d420d3-goog