[PATCH] wifi: mt76: mt7921: validate CLC firmware records

[Laxman Acharya Padhya]

The CLC region is supplied by firmware, but the loader trusts the
region count and each record length. A malformed image can make the
region table pointer precede the firmware buffer, make the record loop
fail to advance, or index phy->clc past its end. Validate the table and
record bounds before dereferencing or copying.

Fixes: 23bdc5d8cadf ("wifi: mt76: mt7921: introduce Country Location
Control support")
Signed-off-by: Laxman Acharya Padhya <acharyalaxman8848 at gmail.com>

---
 drivers/net/wireless/mediatek/mt76/mt7921/mcu.c | 28 +++++++++++++++++++++----
 1 file changed, 24 insertions(+), 4 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mt7921/mcu.c
b/drivers/net/wireless/mediatek/mt76/mt7921/mcu.c
index 25b9437250f7..564dd836e0b3 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7921/mcu.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7921/mcu.c
@@ -415,7 +415,8 @@ static int mt7921_load_clc(struct mt792x_dev *dev,
const char *fw_name)
 	struct mt76_dev *mdev = &dev->mt76;
 	struct mt792x_phy *phy = &dev->phy;
 	const struct firmware *fw;
-	int ret, i, len, offset = 0;
+	size_t clc_len, fw_data_len, len, offset = 0;
+	int ret, i;
 	u8 *clc_base = NULL, hw_encap = 0;

 	dev->phy.clc_chan_conf = 0xff;
@@ -441,13 +442,21 @@ static int mt7921_load_clc(struct mt792x_dev
*dev, const char *fw_name)
 	}

 	hdr = (const void *)(fw->data + fw->size - sizeof(*hdr));
+	if (hdr->n_region > (fw->size - sizeof(*hdr)) / sizeof(*region)) {
+		dev_err(mdev->dev, "Invalid firmware region table\n");
+		ret = -EINVAL;
+		goto out;
+	}
+	fw_data_len = fw->size - sizeof(*hdr) -
+		      hdr->n_region * sizeof(*region);
+
 	for (i = 0; i < hdr->n_region; i++) {
 		region = (const void *)((const u8 *)hdr -
 					(hdr->n_region - i) * sizeof(*region));
 		len = le32_to_cpu(region->len);

 		/* check if we have valid buffer size */
-		if (offset + len > fw->size) {
+		if (len > fw_data_len - offset) {
 			dev_err(mdev->dev, "Invalid firmware region\n");
 			ret = -EINVAL;
 			goto out;
@@ -464,8 +473,19 @@ static int mt7921_load_clc(struct mt792x_dev
*dev, const char *fw_name)
 	if (!clc_base)
 		goto out;

-	for (offset = 0; offset < len; offset += le32_to_cpu(clc->len)) {
+	for (offset = 0; offset < len; offset += clc_len) {
+		if (len - offset < sizeof(*clc)) {
+			ret = -EINVAL;
+			goto out;
+		}
+
 		clc = (const struct mt7921_clc *)(clc_base + offset);
+		clc_len = le32_to_cpu(clc->len);
+		if (clc_len < sizeof(*clc) || clc_len > len - offset ||
+		    clc->idx >= ARRAY_SIZE(phy->clc)) {
+			ret = -EINVAL;
+			goto out;
+		}

 		/* do not init buf again if chip reset triggered */
 		if (phy->clc[clc->idx])
@@ -477,7 +497,7 @@ static int mt7921_load_clc(struct mt792x_dev *dev,
const char *fw_name)
 			continue;

 		phy->clc[clc->idx] = devm_kmemdup(mdev->dev, clc,
-						  le32_to_cpu(clc->len),
+						  clc_len,
 						  GFP_KERNEL);

 		if (!phy->clc[clc->idx]) {