netfilter: br_netfilter: fix panic with metadata_dst skb

Summary

CVECVE-2024-50045
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2024-10-21 20:15:17 UTC
Updated2026-05-12 13:16:16 UTC
DescriptionIn 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---

Risk And Classification

Primary CVSS: v3.1 5.5 MEDIUM from [email protected]

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Problem Types: CWE-476

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Linux Linux Kernel All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 11538d039ac6efcf4f1a6c536e1b87cd3668a9fd f07131239a76cc10d5e82c19d91f53cb55727297 git Not specified
CNA Linux Linux affected 11538d039ac6efcf4f1a6c536e1b87cd3668a9fd 75dfcb758015c97e1accd6340691fca67d363bed git Not specified
CNA Linux Linux affected 11538d039ac6efcf4f1a6c536e1b87cd3668a9fd cce8419b8168f6e7eb637103a47f916f3de8bc81 git Not specified
CNA Linux Linux affected 11538d039ac6efcf4f1a6c536e1b87cd3668a9fd 95c0cff5a1a5d28bf623b92eb5d1a8f56ed30803 git Not specified
CNA Linux Linux affected 11538d039ac6efcf4f1a6c536e1b87cd3668a9fd 78ed917133b118661e1fe62d4a85d5d428ee9568 git Not specified
CNA Linux Linux affected 11538d039ac6efcf4f1a6c536e1b87cd3668a9fd 3453f5839420bfbb85c86c61e49f49ffd0f041c4 git Not specified
CNA Linux Linux affected 11538d039ac6efcf4f1a6c536e1b87cd3668a9fd 915717e0bb9837cc5c101bc545af487bd787239e git Not specified
CNA Linux Linux affected 11538d039ac6efcf4f1a6c536e1b87cd3668a9fd f9ff7665cd128012868098bbd07e28993e314fdb git Not specified
CNA Linux Linux affected 4.11 Not specified
CNA Linux Linux unaffected 4.11 semver Not specified
CNA Linux Linux unaffected 4.19.323 4.19.* semver Not specified
CNA Linux Linux unaffected 5.4.285 5.4.* semver Not specified
CNA Linux Linux unaffected 5.10.227 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.168 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.113 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.57 6.6.* semver Not specified
CNA Linux Linux unaffected 6.11.4 6.11.* semver Not specified
CNA Linux Linux unaffected 6.12 * original_commit_for_fix Not specified
ADP Siemens RUGGEDCOM RST2428P affected V3.2 custom Not specified
ADP Siemens SCALANCE XC-300/XR-300/XC-400/XR-500WG/XR-500 Family affected V3.2 custom Not specified
ADP Siemens SCALANCE XCM-/XRM-/XCH-/XRH-300 Family affected V3.2 custom Not specified
ADP Siemens SIMATIC S7-1500 TM MFP - GNU/Linux Subsystem affected * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.0 V3.1.5 custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.0 V3.1.5 custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP affected V3.1.0 V3.1.5 custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP affected V3.1.0 V3.1.5 custom Not specified
ADP Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.0 V3.1.5 custom Not specified

References

ReferenceSourceLinkTags
cert-portal.siemens.com/productcert/html/ssa-398330.html 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e cert-portal.siemens.com
git.kernel.org/stable/c/f07131239a76cc10d5e82c19d91f53cb55727297 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
lists.debian.org/debian-lts-announce/2025/03/msg00002.html af854a3a-2127-422b-91ae-364da2661108 lists.debian.org
git.kernel.org/stable/c/915717e0bb9837cc5c101bc545af487bd787239e 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
cert-portal.siemens.com/productcert/html/ssa-265688.html 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e cert-portal.siemens.com
git.kernel.org/stable/c/3453f5839420bfbb85c86c61e49f49ffd0f041c4 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/78ed917133b118661e1fe62d4a85d5d428ee9568 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/95c0cff5a1a5d28bf623b92eb5d1a8f56ed30803 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
cert-portal.siemens.com/productcert/html/ssa-355557.html 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e cert-portal.siemens.com
git.kernel.org/stable/c/cce8419b8168f6e7eb637103a47f916f3de8bc81 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
lists.debian.org/debian-lts-announce/2025/01/msg00001.html af854a3a-2127-422b-91ae-364da2661108 lists.debian.org
git.kernel.org/stable/c/f9ff7665cd128012868098bbd07e28993e314fdb 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/75dfcb758015c97e1accd6340691fca67d363bed 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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