linux-kernel - [PATCH] drivers/char/amiserial.c: prevent reading uninitialized stack memory

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Message-ID: <1284587045.6275.98.camel@dan>
Date:	Wed, 15 Sep 2010 17:44:05 -0400
From:	Dan Rosenberg <drosenberg@...curity.com>
To:	linux-kernel@...r.kernel.org
Cc:	security@...nel.org, stable@...nel.org
Subject: [PATCH] drivers/char/amiserial.c: prevent reading uninitialized
 stack memory

The TIOCGICOUNT device ioctl 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>

--- linux-2.6.35.4.orig/drivers/char/amiserial.c	2010-08-26 19:47:12.000000000 -0400
+++ linux-2.6.35.4/drivers/char/amiserial.c	2010-09-15 13:58:00.217343289 -0400
@@ -1342,6 +1342,9 @@ static int rs_ioctl(struct tty_struct *t
 			local_irq_save(flags);
 			cnow = info->state->icount;
 			local_irq_restore(flags);
+
+			memset(&icount, 0, sizeof(struct serial_icounter_struct));
+
 			icount.cts = cnow.cts;
 			icount.dsr = cnow.dsr;
 			icount.rng = cnow.rng;





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