[NET_SCHED]: cls_basic: fix NULL pointer dereference

[NET_SCHED]: cls_basic: fix NULL pointer dereference

[Patrick McHardy]

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These two patches fix the cls_basic crash reported by Chris
Madden and the ingress locking problem.

Please apply, thanks.


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[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>

---
commit f1b9a0694552e18e7a43c292d21abe3b51dfcae2
tree f5ae39c1746fdc1ffbee6c1d90d035ee48ca4904
parent 0a14fe6e5efd0af0f9c6c01e0433445d615d0110
author Patrick McHardy <kaber@trash.net> Tue, 20 Mar 2007 16:08:54 +0100
committer Patrick McHardy <kaber@trash.net> Tue, 20 Mar 2007 16:08:54 +0100

 net/sched/cls_basic.c |   16 +++++++---------
 1 files changed, 7 insertions(+), 9 deletions(-)

diff --git a/net/sched/cls_basic.c b/net/sched/cls_basic.c
index fad08e5..70fe36e 100644
--- a/net/sched/cls_basic.c
+++ b/net/sched/cls_basic.c
@@ -81,6 +81,13 @@ static void basic_put(struct tcf_proto *
 
 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
 	}
 
 	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;

Re: [NET_SCHED]: cls_basic: fix NULL pointer dereference

[David Miller]

From: Patrick McHardy <kaber@trash.net>
Date: Tue, 20 Mar 2007 18:15:00 +0100

> These two patches fix the cls_basic crash reported by Chris
> Madden and the ingress locking problem.
> 
> Please apply, thanks.

Applied, I'll push to -stable, thanks!