[patch] git commit for CVS-2007-4997

1500-CVE-2007-4997-ieee80211-underflow-dos.patch (text/plain), 1.87 KB, created by Mike Pagano on 2007-11-13 00:25:08 UTC

From: John W. Linville <[e-mail]>
Date: Tue, 2 Oct 2007 04:03:54 +0000 (-0700)
Subject: [IEEE80211]: avoid integer underflow for runt rx frames
X-Git-Tag: v2.6.23~42^2
X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Ftorvalds%2Flinux-2.6.git;a=commitdiff_plain;h=04045f98e0457aba7d4e6736f37eed189c48a5f7

[IEEE80211]: avoid integer underflow for runt rx frames

Reported by Chris Evans <[e-mail]>:

> The summary is that an evil 80211 frame can crash out a victim's
> machine. It only applies to drivers using the 80211 wireless code, and
> only then to certain drivers (and even then depends on a card's
> firmware not dropping a dubious packet). I must confess I'm not
> keeping track of Linux wireless support, and the different protocol
> stacks etc.
>
> Details are as follows:
>
> ieee80211_rx() does not explicitly check that "skb->len >= hdrlen".
> There are other skb->len checks, but not enough to prevent a subtle
> off-by-two error if the frame has the IEEE80211_STYPE_QOS_DATA flag
> set.
>
> This leads to integer underflow and crash here:
>
> if (frag != 0)
>    flen -= hdrlen;
>
> (flen is subsequently used as a memcpy length parameter).

How about this?

Signed-off-by: John W. Linville <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>
---

diff --git a/net/ieee80211/ieee80211_rx.c b/net/ieee80211/ieee80211_rx.c
index f2de2e4..6284c99 100644
--- a/net/ieee80211/ieee80211_rx.c
+++ b/net/ieee80211/ieee80211_rx.c
@@ -366,6 +366,12 @@ int ieee80211_rx(struct ieee80211_device *ieee, struct sk_buff *skb,
 	frag = WLAN_GET_SEQ_FRAG(sc);
 	hdrlen = ieee80211_get_hdrlen(fc);
 
+	if (skb->len < hdrlen) {
+		printk(KERN_INFO "%s: invalid SKB length %d\n",
+			dev->name, skb->len);
+		goto rx_dropped;
+	}
+
 	/* Put this code here so that we avoid duplicating it in all
 	 * Rx paths. - Jean II */
 #ifdef CONFIG_WIRELESS_EXT