CVE-2024-56751
- Source
- https://cve.org/CVERecord?id=CVE-2024-56751
- Import Source
- https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2024-56751.json
- JSON Data
- https://api.test.osv.dev/v1/vulns/CVE-2024-56751
- Downstream
- Related
- Published
- 2024-12-29T11:30:16Z
- Modified
- 2026-08-12T03:30:33Z
- Summary
- ipv6: release nexthop on device removal
- Details
-
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.
- Database specific
{ "cna_assigner": "Linux", "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/56xxx/CVE-2024-56751.json" }- References
-
- https://git.kernel.org/stable/c/0e4c6faaef8a24b762a24ffb767280e263ef8e10
- https://git.kernel.org/stable/c/43e25adc80269f917d2a195f0d59f74cdd182955
- https://git.kernel.org/stable/c/77aa9855a878fb43f547ddfbda3127a1e88ad31a
- https://git.kernel.org/stable/c/a3c3f8a4d025acc8c857246ec2b812c59102487a
- https://git.kernel.org/stable/c/b2f26a27ea3f72f75d18330f76f5d1007c791848
- https://git.kernel.org/stable/c/eb02688c5c45c3e7af7e71f036a7144f5639cbfe
- https://lists.debian.org/debian-lts-announce/2025/03/msg00001.html
- https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/56xxx/CVE-2024-56751.json
- https://nvd.nist.gov/vuln/detail/CVE-2024-56751
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Affected packages
Git / git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Affected ranges
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introducedf88d8ea67fbdbac7a64bfa6ed9a2ba27bb822f74Fixed77aa9855a878fb43f547ddfbda3127a1e88ad31aFixedb2f26a27ea3f72f75d18330f76f5d1007c791848Fixed43e25adc80269f917d2a195f0d59f74cdd182955Fixeda3c3f8a4d025acc8c857246ec2b812c59102487aFixed0e4c6faaef8a24b762a24ffb767280e263ef8e10Fixedeb02688c5c45c3e7af7e71f036a7144f5639cbfe
Linux / Kernel
Package
- Name
- Kernel