[PATCH 3.16 236/366] USB: serial: mos7840: fix status-register error handling

Ben Hutchings
2018-11-12T05:48:32Z

From: Johan Hovold <johan@kernel.org>

commit 794744abfffef8b1f3c0c8a4896177d6d13d653d upstream.

Add missing transfer-length sanity check to the status-register
completion handler to avoid leaking bits of uninitialised slab data to
user space.

Fixes: 3f5429746d91 ("USB: Moschip 7840 USB-Serial Driver")
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/usb/serial/mos7840.c | 3 +++
1 file changed, 3 insertions(+)

--- a/drivers/usb/serial/mos7840.c
+++ b/drivers/usb/serial/mos7840.c
@@ -471,6 +471,9 @@ static void mos7840_control_callback(str
}

dev_dbg(dev, "%s urb buffer size is %d\n", __func__, urb->actual_length);
+ if (urb->actual_length < 1)
+ goto out;
+
dev_dbg(dev, "%s mos7840_port->MsrLsr is %d port %d\n", __func__,
mos7840_port->MsrLsr, mos7840_port->port_num);
data = urb->transfer_buffer;