netdev - [PATCH] mt7601u: do not free dma_buf when ivp allocation fails

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Date:	Thu, 25 Feb 2016 22:28:59 +0000
From:	Colin King <colin.king@...onical.com>
To:	Jakub Kicinski <kubakici@...pl>, Kalle Valo <kvalo@...eaurora.org>,
	Matthias Brugger <matthias.bgg@...il.com>,
	linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-mediatek@...ts.infradead.org
Cc:	linux-kernel@...r.kernel.org
Subject: [PATCH] mt7601u: do not free dma_buf when ivp allocation fails

From: Colin Ian King <colin.king@...onical.com>

If the allocation of ivp fails the error handling attempts to
free an uninitialized dma_buf; this data structure just contains
garbage on the stack, so the freeing will cause issues when the
urb, buf and dma fields are cleaned. Fix this by handling the
ivp check and

Signed-off-by: Colin Ian King <colin.king@...onical.com>
---
 drivers/net/wireless/mediatek/mt7601u/mcu.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt7601u/mcu.c b/drivers/net/wireless/mediatek/mt7601u/mcu.c
index fbb1986..06ac657 100644
--- a/drivers/net/wireless/mediatek/mt7601u/mcu.c
+++ b/drivers/net/wireless/mediatek/mt7601u/mcu.c
@@ -359,13 +359,13 @@ mt7601u_upload_firmware(struct mt7601u_dev *dev, const struct mt76_fw *fw)
 	struct mt7601u_dma_buf dma_buf;
 	void *ivb;
 	u32 ilm_len, dlm_len;
-	int i, ret;
+	int i, ret = -ENOMEM;
 
 	ivb = kmemdup(fw->ivb, sizeof(fw->ivb), GFP_KERNEL);
-	if (!ivb || mt7601u_usb_alloc_buf(dev, MCU_FW_URB_SIZE, &dma_buf)) {
-		ret = -ENOMEM;
+	if (!ivb)
+		goto error_ivb;
+	if (mt7601u_usb_alloc_buf(dev, MCU_FW_URB_SIZE, &dma_buf))
 		goto error;
-	}
 
 	ilm_len = le32_to_cpu(fw->hdr.ilm_len) - sizeof(fw->ivb);
 	dev_dbg(dev->dev, "loading FW - ILM %u + IVB %zu\n",
@@ -396,8 +396,9 @@ mt7601u_upload_firmware(struct mt7601u_dev *dev, const struct mt76_fw *fw)
 
 	dev_dbg(dev->dev, "Firmware running!\n");
 error:
-	kfree(ivb);
 	mt7601u_usb_free_buf(dev, &dma_buf);
+error_ivb:
+	kfree(ivb);
 
 	return ret;
 }
-- 
2.7.0