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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Dan Carpenter <dan.carpenter@oracle.com>,
        Kalle Valo <kvalo@codeaurora.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.19 120/361] libertas_tf: prevent underflow in process_cmdrequest()
Date:   Sun, 11 Nov 2018 14:17:47 -0800
Message-Id: <20181111221636.854982070@linuxfoundation.org>
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4.19-stable review patch.  If anyone has any objections, please let me know.

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

From: Dan Carpenter <dan.carpenter@oracle.com>

[ Upstream commit 3348ef6a6a126706d6a73ed40c18d8033df72783 ]

If recvlength is less than MESSAGE_HEADER_LEN (4) we would end up
corrupting memory.

Fixes: c305a19a0d0a ("libertas_tf: usb specific functions")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/wireless/marvell/libertas_tf/if_usb.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- a/drivers/net/wireless/marvell/libertas_tf/if_usb.c
+++ b/drivers/net/wireless/marvell/libertas_tf/if_usb.c
@@ -605,9 +605,10 @@ static inline void process_cmdrequest(in
 {
 	unsigned long flags;
 
-	if (recvlength > LBS_CMD_BUFFER_SIZE) {
+	if (recvlength < MESSAGE_HEADER_LEN ||
+	    recvlength > LBS_CMD_BUFFER_SIZE) {
 		lbtf_deb_usbd(&cardp->udev->dev,
-			     "The receive buffer is too large\n");
+			     "The receive buffer is invalid: %d\n", recvlength);
 		kfree_skb(skb);
 		return;
 	}