Bug 207306 - CVE-2006-4997 IP over ATM clip_mkip dereference freed pointer
CVE-2006-4997 IP over ATM clip_mkip dereference freed pointer
Product: Red Hat Enterprise Linux 2.1
Classification: Red Hat
Component: kernel (Show other bugs)
i386 Linux
medium Severity medium
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Assigned To: Don Howard
Brian Brock
: Security
Depends On:
Blocks: 143573
  Show dependency treegraph
Reported: 2006-09-20 11:57 EDT by Marcel Holtmann
Modified: 2007-11-30 17:06 EST (History)
1 user (show)

See Also:
Fixed In Version: RHSA-2007-0013
Doc Type: Bug Fix
Doc Text:
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Clone Of:
Last Closed: 2007-01-17 05:15:03 EST
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Verified Versions:
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RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---

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Description Marcel Holtmann 2006-09-20 11:57:01 EDT
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;
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 10:13:15 EDT
QE ack for 2.1 maintenance delivery.
Comment 6 Mike Gahagan 2006-12-19 14:11:25 EST
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 05:15:03 EST
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.


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