netdev - [PATCH AUTOSEL 6.2 11/20] wifi: mt76: mt7921: Fix use-after-free in fw features query.

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Message-Id: <20230413023601.74410-11-sashal@kernel.org>
Date:   Wed, 12 Apr 2023 22:35:49 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Ben Greear <greearb@...delatech.com>,
        Lorenzo Bianconi <lorenzo@...nel.org>,
        Felix Fietkau <nbd@....name>, Kalle Valo <kvalo@...nel.org>,
        Sasha Levin <sashal@...nel.org>, ryder.lee@...iatek.com,
        davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
        pabeni@...hat.com, matthias.bgg@...il.com, deren.wu@...iatek.com,
        sean.wang@...iatek.com, mingyen.hsieh@...iatek.com,
        yn.chen@...iatek.com, linux-wireless@...r.kernel.org,
        netdev@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org
Subject: [PATCH AUTOSEL 6.2 11/20] wifi: mt76: mt7921: Fix use-after-free in fw features query.

From: Ben Greear <greearb@...delatech.com>

[ Upstream commit 2ceb76f734e37833824b7fab6af17c999eb48d2b ]

Stop referencing 'features' memory after release_firmware is called.

Fixes this crash:

RIP: 0010:mt7921_check_offload_capability+0x17d
mt7921_pci_probe+0xca/0x4b0
...

Signed-off-by: Ben Greear <greearb@...delatech.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@...nel.org>
Acked-by: Felix Fietkau <nbd@....name>
Signed-off-by: Kalle Valo <kvalo@...nel.org>
Link: https://lore.kernel.org/r/51fd8f76494348aa9ecbf0abc471ebe47a983dfd.1679502607.git.lorenzo@kernel.org
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/net/wireless/mediatek/mt76/mt7921/init.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mt7921/init.c b/drivers/net/wireless/mediatek/mt76/mt7921/init.c
index d4b681d7e1d22..f2c6ec4d8e2ee 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7921/init.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7921/init.c
@@ -162,12 +162,12 @@ mt7921_mac_init_band(struct mt7921_dev *dev, u8 band)
 
 u8 mt7921_check_offload_capability(struct device *dev, const char *fw_wm)
 {
-	struct mt7921_fw_features *features = NULL;
 	const struct mt76_connac2_fw_trailer *hdr;
 	struct mt7921_realease_info *rel_info;
 	const struct firmware *fw;
 	int ret, i, offset = 0;
 	const u8 *data, *end;
+	u8 offload_caps = 0;
 
 	ret = request_firmware(&fw, fw_wm, dev);
 	if (ret)
@@ -199,7 +199,10 @@ u8 mt7921_check_offload_capability(struct device *dev, const char *fw_wm)
 		data += sizeof(*rel_info);
 
 		if (rel_info->tag == MT7921_FW_TAG_FEATURE) {
+			struct mt7921_fw_features *features;
+
 			features = (struct mt7921_fw_features *)data;
+			offload_caps = features->data;
 			break;
 		}
 
@@ -209,7 +212,7 @@ u8 mt7921_check_offload_capability(struct device *dev, const char *fw_wm)
 out:
 	release_firmware(fw);
 
-	return features ? features->data : 0;
+	return offload_caps;
 }
 EXPORT_SYMBOL_GPL(mt7921_check_offload_capability);
 
-- 
2.39.2