[PATCH 3/3] wifi: mwifiex: Sanity check tlv_len and tlv_bitmap_len

[Gustavo A. R. Silva]

Add sanity checks for both `tlv_len` and `tlv_bitmap_len` before
decoding data from `event_buf`.

This prevents any malicious or buggy firmware from overflowing
`event_buf` through large values for `tlv_len` or `tlv_bitmap_len`.

Suggested-by: Dan Williams <dcbw@xxxxxxxxxx>
Signed-off-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx>
---
 .../net/wireless/marvell/mwifiex/11n_rxreorder.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/net/wireless/marvell/mwifiex/11n_rxreorder.c b/drivers/net/wireless/marvell/mwifiex/11n_rxreorder.c
index 735aac52bdc4..9ee3b9f1e9ce 100644
--- a/drivers/net/wireless/marvell/mwifiex/11n_rxreorder.c
+++ b/drivers/net/wireless/marvell/mwifiex/11n_rxreorder.c
@@ -921,6 +921,14 @@ void mwifiex_11n_rxba_sync_event(struct mwifiex_private *priv,
 	while (tlv_buf_left > sizeof(*tlv_rxba)) {
 		tlv_type = le16_to_cpu(tlv_rxba->header.type);
 		tlv_len  = le16_to_cpu(tlv_rxba->header.len);
+		if (size_add(sizeof(tlv_rxba->header), tlv_len) > tlv_buf_left) {
+			mwifiex_dbg(priv->adapter, WARN,
+				    "TLV size (%ld) overflows event_buf (%d)\n",
+				    size_add(sizeof(tlv_rxba->header), tlv_len),
+				    tlv_buf_left);
+			return;
+		}
+
 		if (tlv_type != TLV_TYPE_RXBA_SYNC) {
 			mwifiex_dbg(priv->adapter, ERROR,
 				    "Wrong TLV id=0x%x\n", tlv_type);
@@ -929,6 +937,14 @@ void mwifiex_11n_rxba_sync_event(struct mwifiex_private *priv,
 
 		tlv_seq_num = le16_to_cpu(tlv_rxba->seq_num);
 		tlv_bitmap_len = le16_to_cpu(tlv_rxba->bitmap_len);
+		if (size_add(sizeof(*tlv_rxba), tlv_bitmap_len) > tlv_buf_left) {
+			mwifiex_dbg(priv->adapter, WARN,
+				    "TLV size (%ld) overflows event_buf (%d)\n",
+				    size_add(sizeof(*tlv_rxba), tlv_bitmap_len),
+				    tlv_buf_left);
+			return;
+		}
+
 		mwifiex_dbg(priv->adapter, INFO,
 			    "%pM tid=%d seq_num=%d bitmap_len=%d\n",
 			    tlv_rxba->mac, tlv_rxba->tid, tlv_seq_num,
-- 
2.34.1