Homepage

NULL Pointer Dereference Affecting kernel-debug-core package, versions *

Severity

 Recommended
0.0
medium
0
10

Based on Red Hat Enterprise Linux security rating.

Threat Intelligence

EPSS
0.04% (5th 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-RHEL8-KERNELDEBUGCORE-8284319
  • published23 Oct 2024
  • disclosed21 Oct 2024
Report a new vulnerability Found a mistake?

Introduced: 21 Oct 2024

CVE-2024-50045  (opens in a new tab)
CWE-476  (opens in a new tab)

How to fix?

There is no fixed version for RHEL:8 kernel-debug-core.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-debug-core package and not the kernel-debug-core package as distributed by RHEL. See How to fix? for RHEL:8 relevant fixed versions and status.

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

netfilter: br_netfilter: fix panic with metadata_dst skb

Fix a kernel panic in the br_netfilter module when sending untagged traffic via a VxLAN device. This happens during the check for fragmentation in br_nf_dev_queue_xmit.

It is dependent on:

  1. the br_netfilter module being loaded;
  2. net.bridge.bridge-nf-call-iptables set to 1;
  3. a bridge with a VxLAN (single-vxlan-device) netdevice as a bridge port;
  4. untagged frames with size higher than the VxLAN MTU forwarded/flooded

When forwarding the untagged packet to the VxLAN bridge port, before the netfilter hooks are called, br_handle_egress_vlan_tunnel is called and changes the skb_dst to the tunnel dst. The tunnel_dst is a metadata type of dst, i.e., skb_valid_dst(skb) is false, and metadata->dst.dev is NULL.

Then in the br_netfilter hooks, in br_nf_dev_queue_xmit, there's a check for frames that needs to be fragmented: frames with higher MTU than the VxLAN device end up calling br_nf_ip_fragment, which in turns call ip_skb_dst_mtu.

The ip_dst_mtu tries to use the skb_dst(skb) as if it was a valid dst with valid dst->dev, thus the crash.

This case was never supported in the first place, so drop the packet instead.

PING 10.0.0.2 (10.0.0.2) from 0.0.0.0 h1-eth0: 2000(2028) bytes of data. [ 176.291791] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000110 [ 176.292101] Mem abort info: [ 176.292184] ESR = 0x0000000096000004 [ 176.292322] EC = 0x25: DABT (current EL), IL = 32 bits [ 176.292530] SET = 0, FnV = 0 [ 176.292709] EA = 0, S1PTW = 0 [ 176.292862] FSC = 0x04: level 0 translation fault [ 176.293013] Data abort info: [ 176.293104] ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000 [ 176.293488] CM = 0, WnR = 0, TnD = 0, TagAccess = 0 [ 176.293787] GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0 [ 176.293995] user pgtable: 4k pages, 48-bit VAs, pgdp=0000000043ef5000 [ 176.294166] [0000000000000110] pgd=0000000000000000, p4d=0000000000000000 [ 176.294827] Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP [ 176.295252] Modules linked in: vxlan ip6_udp_tunnel udp_tunnel veth br_netfilter bridge stp llc ipv6 crct10dif_ce [ 176.295923] CPU: 0 PID: 188 Comm: ping Not tainted 6.8.0-rc3-g5b3fbd61b9d1 #2 [ 176.296314] Hardware name: linux,dummy-virt (DT) [ 176.296535] pstate: 80000005 (Nzcv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) [ 176.296808] pc : br_nf_dev_queue_xmit+0x390/0x4ec [br_netfilter] [ 176.297382] lr : br_nf_dev_queue_xmit+0x2ac/0x4ec [br_netfilter] [ 176.297636] sp : ffff800080003630 [ 176.297743] x29: ffff800080003630 x28: 0000000000000008 x27: ffff6828c49ad9f8 [ 176.298093] x26: ffff6828c49ad000 x25: 0000000000000000 x24: 00000000000003e8 [ 176.298430] x23: 0000000000000000 x22: ffff6828c4960b40 x21: ffff6828c3b16d28 [ 176.298652] x20: ffff6828c3167048 x19: ffff6828c3b16d00 x18: 0000000000000014 [ 176.298926] x17: ffffb0476322f000 x16: ffffb7e164023730 x15: 0000000095744632 [ 176.299296] x14: ffff6828c3f1c880 x13: 0000000000000002 x12: ffffb7e137926a70 [ 176.299574] x11: 0000000000000001 x10: ffff6828c3f1c898 x9 : 0000000000000000 [ 176.300049] x8 : ffff6828c49bf070 x7 : 0008460f18d5f20e x6 : f20e0100bebafeca [ 176.300302] x5 : ffff6828c7f918fe x4 : ffff6828c49bf070 x3 : 0000000000000000 [ 176.300586] x2 : 0000000000000000 x1 : ffff6828c3c7ad00 x0 : ffff6828c7f918f0 [ 176.300889] Call trace: [ 176.301123] br_nf_dev_queue_xmit+0x390/0x4ec [br_netfilter] [ 176.301411] br_nf_post_routing+0x2a8/0x3e4 [br_netfilter] [ 176.301703] nf_hook_slow+0x48/0x124 [ 176.302060] br_forward_finish+0xc8/0xe8 [bridge] [ 176.302371] br_nf_hook_thresh+0x124/0x134 [br_netfilter] [ 176.302605] br_nf_forward_finish+0x118/0x22c [br_netfilter] [ 176.302824] br_nf_forward_ip.part.0+0x264/0x290 [br_netfilter] [ 176.303136] br_nf_forward+0x2b8/0x4e0 [br_netfilter] [ 176.303359] nf_hook_slow+0x48/0x124 [ 176.303 ---truncated---

CVSS Scores

version 3.1