rsi: fix a double free bug in rsi_91x_deinit()

`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>

diff --git a/drivers/net/wireless/rsi/rsi_91x_usb.c b/drivers/net/wireless/rsi/rsi_91x_usb.c
index f5048d4..760eaff 100644 (file)
--- 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;
 }