NULL Pointer Dereference Affecting kernel-zfcpdump package, versions <0:5.14.0-362.8.1.el9_3


Severity

Recommended
high

Based on Red Hat Enterprise Linux security rating.

Threat Intelligence

EPSS
0.04% (12th percentile)

Do your applications use this vulnerable package?

In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.

Test your applications

Snyk Learn

Learn about NULL Pointer Dereference vulnerabilities in an interactive lesson.

Start learning
  • Snyk IDSNYK-RHEL9-KERNELZFCPDUMP-8461744
  • published5 Dec 2024
  • disclosed24 May 2024

Introduced: 24 May 2024

CVE-2021-47515  (opens in a new tab)
CWE-476  (opens in a new tab)

How to fix?

Upgrade RHEL:9 kernel-zfcpdump to version 0:5.14.0-362.8.1.el9_3 or higher.
This issue was patched in RHSA-2023:6583.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-zfcpdump package and not the kernel-zfcpdump package as distributed by RHEL. See How to fix? for RHEL:9 relevant fixed versions and status.

In the Linux kernel, the following vulnerability has been resolved:

seg6: fix the iif in the IPv6 socket control block

When an IPv4 packet is received, the ip_rcv_core(...) sets the receiving interface index into the IPv4 socket control block (v5.16-rc4, net/ipv4/ip_input.c line 510):

IPCB(skb)-&gt;iif = skb-&gt;skb_iif;

If that IPv4 packet is meant to be encapsulated in an outer IPv6+SRH header, the seg6_do_srh_encap(...) performs the required encapsulation. In this case, the seg6_do_srh_encap function clears the IPv6 socket control block (v5.16-rc4 net/ipv6/seg6_iptunnel.c line 163):

memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));

The memset(...) was introduced in commit ef489749aae5 ("ipv6: sr: clear IP6CB(skb) on SRH ip4ip6 encapsulation") a long time ago (2019-01-29).

Since the IPv6 socket control block and the IPv4 socket control block share the same memory area (skb->cb), the receiving interface index info is lost (IP6CB(skb)->iif is set to zero).

As a side effect, that condition triggers a NULL pointer dereference if commit 0857d6f8c759 ("ipv6: When forwarding count rx stats on the orig netdev") is applied.

To fix that issue, we set the IP6CB(skb)->iif with the index of the receiving interface once again.

CVSS Scores

version 3.1