[PATCH 6.6 184/474] wifi: mt76: mt7921: fix a potential clc buffer length underflow

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

6.6-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Leon Yen <leon.yen@mediatek.com>

commit 5373f8b19e568b5c217832b9bbef165bd2b2df14 upstream.

The buf_len is used to limit the iterations for retrieving the country
power setting and may underflow under certain conditions due to changes
in the power table in CLC.

This underflow leads to an almost infinite loop or an invalid power
setting resulting in driver initialization failure.

Cc: stable@vger.kernel.org
Fixes: fa6ad88e023d ("wifi: mt76: mt7921: fix country count limitation for CLC")
Signed-off-by: Leon Yen <leon.yen@mediatek.com>
Signed-off-by: Ming Yen Hsieh <mingyen.hsieh@mediatek.com>
Link: https://patch.msgid.link/20251009020158.1923429-1-mingyen.hsieh@mediatek.com
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/wireless/mediatek/mt76/mt7921/mcu.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/drivers/net/wireless/mediatek/mt76/mt7921/mcu.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7921/mcu.c
@@ -1155,6 +1155,9 @@ int __mt7921_mcu_set_clc(struct mt792x_d
 		u16 len = le16_to_cpu(rule->len);
 		u16 offset = len + sizeof(*rule);
 
+		if (buf_len < offset)
+			break;
+
 		pos += offset;
 		buf_len -= offset;
 		if (rule->alpha2[0] != alpha2[0] ||