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From: Chris Wright <chrisw@osdl.org>
To: linux-kernel@vger.kernel.org, stable@kernel.org
Cc: shemminger@osdl.org, kaber@trash.net, torvalds@osdl.org,
	akpm@osdl.org, alan@lxorguk.ukuu.org.uk, jmforbes@linuxtx.org,
	zwane@arm.linux.org.uk, cliffw@osdl.org, tytso@mit.edu,
	rddunlap@osdl.org
Subject: [5/9] [TUN] Fix check for underflow
Date: Wed, 16 Mar 2005 15:55:02 -0800	[thread overview]
Message-ID: <20050316235502.GD5389@shell0.pdx.osdl.net> (raw)
In-Reply-To: <20050316235336.GY5389@shell0.pdx.osdl.net>

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

----

From: Stephen Hemminger <shemminger@osdl.org>

http://bugme.osdl.org/show_bug.cgi?id=4279
Summary: When I try to start vpnc the net/core/skbuff.c:91 crash

This check is wrong, gcc optimizes it away:

                if ((len -= sizeof(pi)) > len)
			return -EINVAL;

This could be responsible for the BUG. If len is 2 or 3 and TUN_NO_PI
isn't set it underflows. alloc_skb() allocates len + 2, which is 0 or
1 byte. skb_reserve tries to reserve 2 bytes and things explode in
skb_put.

[TUN]: Fix check for underflow

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Chris Wright <chrisw@osdl.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff -Nru a/drivers/net/tun.c b/drivers/net/tun.c
--- a/drivers/net/tun.c	2005-03-04 19:41:56 +01:00
+++ b/drivers/net/tun.c	2005-03-04 19:41:56 +01:00
@@ -229,7 +229,7 @@
 	size_t len = count;
 
 	if (!(tun->flags & TUN_NO_PI)) {
-		if ((len -= sizeof(pi)) > len)
+		if ((len -= sizeof(pi)) > count)
 			return -EINVAL;
 
 		if(memcpy_fromiovec((void *)&pi, iv, sizeof(pi)))

  parent reply	other threads:[~2005-03-16 23:59 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-03-16 23:53 [0/9] -stable review Chris Wright
2005-03-16 23:54 ` [1/9] [ALSA] Fix stereo mutes on Surround volume control Chris Wright
2005-03-16 23:54 ` [2/9] Possible AMD8111e free irq issue Chris Wright
2005-03-17  0:19   ` Ian Pilcher
2005-03-17  1:03     ` Chris Wright
2005-03-17  1:13       ` Ian Pilcher
2005-03-17  2:00     ` Jeff Garzik
2005-03-16 23:54 ` [3/9] [IPSEC]: Fix __xfrm_find_acq_byseq() Chris Wright
2005-03-16 23:54 ` [4/9] NetROM locking Chris Wright
2005-03-16 23:55 ` Chris Wright [this message]
2005-03-17  0:13   ` [5/9] [TUN] Fix check for underflow Patrick McHardy
2005-03-17  0:23     ` Chris Wright
2005-03-16 23:55 ` [6/9] tasklist left locked Chris Wright
2005-03-16 23:55 ` [7/9] Timercode race in AX.25 Chris Wright
2005-03-16 23:55 ` [8/9] Possible VIA-Rhine free irq issue Chris Wright
2005-03-16 23:55 ` [9/9] Fix kernel panic on receive with WAN Hitachi SCA HD6457x Chris Wright

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