Linux Kernel up to 6.1.119/6.6.63/6.11.10/6.12.1 pmtu.sh ip6_dst_ifdown iteration

Summaryinfo

A vulnerability has been found in Linux Kernel up to 6.1.119/6.6.63/6.11.10/6.12.1 and classified as problematic. This issue affects the function ip6_dst_ifdown of the file pmtu.sh. The manipulation leads to iteration. This vulnerability is listed as CVE-2024-56751. There is no available exploit. The affected component should be upgraded.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.1.119/6.6.63/6.11.10/6.12.1 and classified as problematic. This issue affects the function ip6_dst_ifdown of the file pmtu.sh. The manipulation with an unknown input leads to a iteration vulnerability. Using CWE to declare the problem leads to CWE-834. The product performs an iteration or loop without sufficiently limiting the number of times that the loop is executed. Impacted is availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: ipv6: release nexthop on device removal The CI is hitting some aperiodic hangup at device removal time in the pmtu.sh self-test: unregister_netdevice: waiting for veth_A-R1 to become free. Usage count = 6 ref_tracker: veth_A-R1@ffff888013df15d8 has 1/5 users at dst_init+0x84/0x4a0 dst_alloc+0x97/0x150 ip6_dst_alloc+0x23/0x90 ip6_rt_pcpu_alloc+0x1e6/0x520 ip6_pol_route+0x56f/0x840 fib6_rule_lookup+0x334/0x630 ip6_route_output_flags+0x259/0x480 ip6_dst_lookup_tail.constprop.0+0x5c2/0x940 ip6_dst_lookup_flow+0x88/0x190 udp_tunnel6_dst_lookup+0x2a7/0x4c0 vxlan_xmit_one+0xbde/0x4a50 [vxlan] vxlan_xmit+0x9ad/0xf20 [vxlan] dev_hard_start_xmit+0x10e/0x360 __dev_queue_xmit+0xf95/0x18c0 arp_solicit+0x4a2/0xe00 neigh_probe+0xaa/0xf0 While the first suspect is the dst_cache, explicitly tracking the dst owing the last device reference via probes proved such dst is held by the nexthop in the originating fib6_info. Similar to commit f5b51fe804ec ("ipv6: route: purge exception on removal"), we need to explicitly release the originating fib info when disconnecting a to-be-removed device from a live ipv6 dst: move the fib6_info cleanup into ip6_dst_ifdown(). Tested running: ./pmtu.sh cleanup_ipv6_exception in a tight loop for more than 400 iterations with no spat, running an unpatched kernel I observed a splat every ~10 iterations.

The advisory is shared at git.kernel.org. The identification of this vulnerability is CVE-2024-56751 since 12/29/2024. The exploitation is known to be difficult. Technical details are known, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 214608 (Amazon Linux 2023 : bpftool, kernel, kernel-devel (ALAS2023-2025-809)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.1.120, 6.6.64, 6.11.11 or 6.12.2 eliminates this vulnerability. Applying the patch b2f26a27ea3f72f75d18330f76f5d1007c791848/43e25adc80269f917d2a195f0d59f74cdd182955/a3c3f8a4d025acc8c857246ec2b812c59102487a/0e4c6faaef8a24b762a24ffb767280e263ef8e10/eb02688c5c45c3e7af7e71f036a7144f5639cbfe is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (214608) and CERT Bund (WID-SEC-2025-1439). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Affected

• SUSE Linux
• Dell Secure Connect Gateway

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.1.119
• 6.6.0
• 6.6.1
• 6.6.2
• 6.6.3
• 6.6.4
• 6.6.5
• 6.6.6
• 6.6.7
• 6.6.8
• 6.6.9
• 6.6.10
• 6.6.11
• 6.6.12
• 6.6.13
• 6.6.14
• 6.6.15
• 6.6.16
• 6.6.17
• 6.6.18
• 6.6.19
• 6.6.20
• 6.6.21
• 6.6.22
• 6.6.23
• 6.6.24
• 6.6.25
• 6.6.26
• 6.6.27
• 6.6.28
• 6.6.29
• 6.6.30
• 6.6.31
• 6.6.32
• 6.6.33
• 6.6.34
• 6.6.35
• 6.6.36
• 6.6.37
• 6.6.38
• 6.6.39
• 6.6.40
• 6.6.41
• 6.6.42
• 6.6.43
• 6.6.44
• 6.6.45
• 6.6.46
• 6.6.47
• 6.6.48
• 6.6.49
• 6.6.50
• 6.6.51
• 6.6.52
• 6.6.53
• 6.6.54
• 6.6.55
• 6.6.56
• 6.6.57
• 6.6.58
• 6.6.59
• 6.6.60
• 6.6.61
• 6.6.62
• 6.6.63
• 6.11.0
• 6.11.1
• 6.11.2
• 6.11.3
• 6.11.4
• 6.11.5
• 6.11.6
• 6.11.7
• 6.11.8
• 6.11.9
• 6.11.10
• 6.12.0
• 6.12.1

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

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CPE 2.2info

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CVSSv4info

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CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

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