{"id":"DEBIAN-CVE-2024-56751","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 \tdst_init+0x84/0x4a0 \tdst_alloc+0x97/0x150 \tip6_dst_alloc+0x23/0x90 \tip6_rt_pcpu_alloc+0x1e6/0x520 \tip6_pol_route+0x56f/0x840 \tfib6_rule_lookup+0x334/0x630 \tip6_route_output_flags+0x259/0x480 \tip6_dst_lookup_tail.constprop.0+0x5c2/0x940 \tip6_dst_lookup_flow+0x88/0x190 \tudp_tunnel6_dst_lookup+0x2a7/0x4c0 \tvxlan_xmit_one+0xbde/0x4a50 [vxlan] \tvxlan_xmit+0x9ad/0xf20 [vxlan] \tdev_hard_start_xmit+0x10e/0x360 \t__dev_queue_xmit+0xf95/0x18c0 \tarp_solicit+0x4a2/0xe00 \tneigh_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.","modified":"2026-09-15T09:03:17.553231586Z","published":"2024-12-29T12:15:08.640Z","upstream":["CVE-2024-56751"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2024-56751"}],"affected":[{"package":{"name":"linux","ecosystem":"Debian:12","purl":"pkg:deb/debian/linux?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.1.123-1"}]}],"versions":["6.1.106-1","6.1.106-2","6.1.106-3","6.1.112-1","6.1.115-1","6.1.119-1","6.1.27-1","6.1.37-1","6.1.38-1","6.1.38-2","6.1.38-2~bpo11+1","6.1.38-3","6.1.38-4","6.1.38-4~bpo11+1","6.1.52-1","6.1.55-1","6.1.55-1~bpo11+1","6.1.64-1","6.1.66-1","6.1.67-1","6.1.69-1","6.1.69-1~bpo11+1","6.1.76-1","6.1.76-1~bpo11+1","6.1.82-1","6.1.85-1","6.1.90-1","6.1.90-1~bpo11+1","6.1.94-1","6.1.94-1~bpo11+1","6.1.98-1","6.1.99-1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2024-56751.json"}},{"package":{"name":"linux","ecosystem":"Debian:13","purl":"pkg:deb/debian/linux?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.12.3-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2024-56751.json"}},{"package":{"name":"linux","ecosystem":"Debian:14","purl":"pkg:deb/debian/linux?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.12.3-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2024-56751.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"}]}