From: Patrick McHardy <kaber@trash.net>
Date: Sun, 25 Mar 2007 05:13:06 +0000 (-0700)
Subject: [NET_SCHED]: cls_basic: fix NULL pointer dereference
X-Git-Tag: v2.6.21-rc6~114^2~5
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d3fa76ee6b4a8dd0efda4e78e96f5b19533b3dea;p=linux-2.6

[NET_SCHED]: cls_basic: fix NULL pointer dereference

cls_basic doesn't allocate tp->root before it is linked into the
active classifier list, resulting in a NULL pointer dereference
when packets hit the classifier before its ->change function is
called.

Reported by Chris Madden <chris@reflexsecurity.com>

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/net/sched/cls_basic.c b/net/sched/cls_basic.c
index fad08e521c..70fe36eb66 100644
--- a/net/sched/cls_basic.c
+++ b/net/sched/cls_basic.c
@@ -81,6 +81,13 @@ static void basic_put(struct tcf_proto *tp, unsigned long f)
 
 static int basic_init(struct tcf_proto *tp)
 {
+	struct basic_head *head;
+
+	head = kzalloc(sizeof(*head), GFP_KERNEL);
+	if (head == NULL)
+		return -ENOBUFS;
+	INIT_LIST_HEAD(&head->flist);
+	tp->root = head;
 	return 0;
 }
 
@@ -176,15 +183,6 @@ static int basic_change(struct tcf_proto *tp, unsigned long base, u32 handle,
 	}
 
 	err = -ENOBUFS;
-	if (head == NULL) {
-		head = kzalloc(sizeof(*head), GFP_KERNEL);
-		if (head == NULL)
-			goto errout;
-
-		INIT_LIST_HEAD(&head->flist);
-		tp->root = head;
-	}
-
 	f = kzalloc(sizeof(*f), GFP_KERNEL);
 	if (f == NULL)
 		goto errout;