[PATCH] wifi: mt76: mt7915: validate default EEPROM firmware size

[Ridham Khurana]

mt7915_eeprom_load_default() checks that the default EEPROM firmware was
loaded, but not how big it is. It then copies mt7915_eeprom_size() bytes
out of it, which is 3584 on MT7915 and 4096 on MT7916.

If the file is smaller than that, the copy reads past the end of the
firmware buffer. The extra bytes are whatever happens to follow it in
memory, and they end up in the EEPROM buffer that is later used for band
configuration, chainmask and TX power.

Check the size before copying, the same way
mt7996_eeprom_check_or_use_default() already does.

Fixes: bbc1d4154ec1 ("mt76: mt7915: add default calibrated data support")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Ridham Khurana <khurana.ridham222@xxxxxxxxx>
---
Based on next-20260828; applies cleanly to v7.2.

 drivers/net/wireless/mediatek/mt76/mt7915/eeprom.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/net/wireless/mediatek/mt76/mt7915/eeprom.c b/drivers/net/wireless/mediatek/mt76/mt7915/eeprom.c
index fe7b29ebc0bf..145d14a1012d 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7915/eeprom.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7915/eeprom.c
@@ -111,6 +111,12 @@ mt7915_eeprom_load_default(struct mt7915_dev *dev)
 		goto out;
 	}
 
+	if (fw->size < mt7915_eeprom_size(dev)) {
+		dev_err(dev->mt76.dev, "Invalid default bin size\n");
+		ret = -EINVAL;
+		goto out;
+	}
+
 	memcpy(eeprom, fw->data, mt7915_eeprom_size(dev));
 	dev->flash_mode = true;
 
-- 
2.47.3