Bug 207306

Summary: CVE-2006-4997 IP over ATM clip_mkip dereference freed pointer
Product: Red Hat Enterprise Linux 2.1 Reporter: Marcel Holtmann <holtmann>
Component: kernelAssignee: Don Howard <dhoward>
Status: CLOSED ERRATA QA Contact: Brian Brock <bbrock>
Severity: medium Docs Contact:
Priority: medium    
Version: 2.1CC: security-response-team
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: i386   
OS: Linux   
Whiteboard: impact=moderate,reported=20060912,source=lkml,public=20060912
Fixed In Version: RHSA-2007-0013 Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2007-01-17 10:15:03 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On:    
Bug Blocks: 143573    

Description Marcel Holtmann 2006-09-20 15:57:01 UTC
Reported by ADLab, Venustech info Ltd CHINA:

There is a vulnerability in function clip_mkip() in net/atm/clip.c. When
re-processing received data, a struct sk_buff pointer skb may be dereferenced
after a free operation. It will lead to a kernel panic and denying further service.
 
clip_mkip (clip.c):

502         while ((skb = skb_dequeue(&copy)) != NULL)
503                 if (!clip_devs) {
504                         atm_return(vcc,skb->truesize);
505                         kfree_skb(skb);
506                 }
507                 else {
508                         unsigned int len = skb->len;
509
510                         clip_push(vcc,skb);
511                         PRIV(skb->dev)->stats.rx_packets--;
512                         PRIV(skb->dev)->stats.rx_bytes -= len;
513                 }
 
At line 511, PRIV(skb->dev) reference skb->dev; but after call clip_push at line
510, skb may be freed.
 
clip_push (clip.c):

198 static void clip_push(struct atm_vcc *vcc,struct sk_buff *skb)
199 {

	......

234         memset(ATM_SKB(skb), 0, sizeof(struct atm_skb_data));
235         netif_rx(skb);
236 }
 
netif_rx (dev.c):

1392 int netif_rx(struct sk_buff *skb)
1393 {

	......

1428         kfree_skb(skb);	//drop skb
1429         return NET_RX_DROP;
1430 }

In netif_rx(), skb may be dropped during processing for congestion control or by
the protocol layers; the return value NET_RX_DROP is used to identify skb
pointer arg is dropped(freed).

Comment 3 Jay Turner 2006-10-10 14:13:15 UTC
QE ack for 2.1 maintenance delivery.

Comment 6 Mike Gahagan 2006-12-19 19:11:25 UTC
Verified that the fix for this is in linux-2.4.9-smallfixes.patch and is being
applied to e.71.


Comment 8 Red Hat Bugzilla 2007-01-17 10:15:03 UTC
An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on the solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.

http://rhn.redhat.com/errata/RHSA-2007-0013.html