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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, Hui Peng <benquike@gmail.com>,
        Mathias Payer <mathias.payer@nebelwelt.net>,
        Guenter Roeck <linux@roeck-us.net>,
        Kalle Valo <kvalo@codeaurora.org>
Subject: [PATCH 5.2 84/85] rsi: fix a double free bug in rsi_91x_deinit()
Date:   Wed, 18 Sep 2019 08:19:42 +0200
Message-Id: <20190918061238.025709947@linuxfoundation.org>
In-Reply-To: <20190918061234.107708857@linuxfoundation.org>
References: <20190918061234.107708857@linuxfoundation.org>
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From: Hui Peng <benquike@gmail.com>

commit 8b51dc7291473093c821195c4b6af85fadedbc2f upstream.

`dev` (struct rsi_91x_usbdev *) field of adapter
(struct rsi_91x_usbdev *) is allocated  and initialized in
`rsi_init_usb_interface`. If any error is detected in information
read from the device side,  `rsi_init_usb_interface` will be
freed. However, in the higher level error handling code in
`rsi_probe`, if error is detected, `rsi_91x_deinit` is called
again, in which `dev` will be freed again, resulting double free.

This patch fixes the double free by removing the free operation on
`dev` in `rsi_init_usb_interface`, because `rsi_91x_deinit` is also
used in `rsi_disconnect`, in that code path, the `dev` field is not
 (and thus needs to be) freed.

This bug was found in v4.19, but is also present in the latest version
of kernel. Fixes CVE-2019-15504.

Reported-by: Hui Peng <benquike@gmail.com>
Reported-by: Mathias Payer <mathias.payer@nebelwelt.net>
Signed-off-by: Hui Peng <benquike@gmail.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/net/wireless/rsi/rsi_91x_usb.c |    1 -
 1 file changed, 1 deletion(-)

--- a/drivers/net/wireless/rsi/rsi_91x_usb.c
+++ b/drivers/net/wireless/rsi/rsi_91x_usb.c
@@ -645,7 +645,6 @@ fail_rx:
 	kfree(rsi_dev->tx_buffer);
 
 fail_eps:
-	kfree(rsi_dev);
 
 	return status;
 }