linux-kernel - [02/80] USB: serial/mos*: prevent reading uninitialized stack memory

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Date:	Fri, 24 Sep 2010 09:23:50 -0700
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Dan Rosenberg <dan.j.rosenberg@...il.com>
Subject: [02/80] USB: serial/mos*: prevent reading uninitialized stack memory

2.6.35-stable review patch.  If anyone has any objections, please let us know.

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

From: Dan Rosenberg <drosenberg@...curity.com>

commit a0846f1868b11cd827bdfeaf4527d8b1b1c0b098 upstream.

The TIOCGICOUNT device ioctl in both mos7720.c and mos7840.c allows
unprivileged users to read uninitialized stack memory, because the
"reserved" member of the serial_icounter_struct struct declared on the
stack is not altered or zeroed before being copied back to the user.
This patch takes care of it.

Signed-off-by: Dan Rosenberg <dan.j.rosenberg@...il.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 drivers/usb/serial/mos7720.c |    3 +++
 drivers/usb/serial/mos7840.c |    3 +++
 2 files changed, 6 insertions(+)

--- a/drivers/usb/serial/mos7720.c
+++ b/drivers/usb/serial/mos7720.c
@@ -2024,6 +2024,9 @@ static int mos7720_ioctl(struct tty_stru
 
 	case TIOCGICOUNT:
 		cnow = mos7720_port->icount;
+
+		memset(&icount, 0, sizeof(struct serial_icounter_struct));
+
 		icount.cts = cnow.cts;
 		icount.dsr = cnow.dsr;
 		icount.rng = cnow.rng;
--- a/drivers/usb/serial/mos7840.c
+++ b/drivers/usb/serial/mos7840.c
@@ -2285,6 +2285,9 @@ static int mos7840_ioctl(struct tty_stru
 	case TIOCGICOUNT:
 		cnow = mos7840_port->icount;
 		smp_rmb();
+
+		memset(&icount, 0, sizeof(struct serial_icounter_struct));
+
 		icount.cts = cnow.cts;
 		icount.dsr = cnow.dsr;
 		icount.rng = cnow.rng;


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