cbcvebase.
CVE-2024-56751
published 2024-12-29

CVE-2024-56751: 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…

PriorityP419medium5.5CVSS 3.1
AVLACLPRLUINSUCNINAH
EPSS
0.21%
10.9th percentile
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.

Affected

22 ranges
VendorProductVersion rangeFixed in
debianlinux< linux 6.1.123-1 (bookworm)linux 6.1.123-1 (bookworm)
debianlinux-6.1< linux 6.1.123-1 (bookworm)linux 6.1.123-1 (bookworm)
linuxlinux
linuxlinux>= f88d8ea67fbdbac7a64bfa6ed9a2ba27bb822f74 < 77aa9855a878fb43f547ddfbda3127a1e88ad31a77aa9855a878fb43f547ddfbda3127a1e88ad31a
linuxlinux>= f88d8ea67fbdbac7a64bfa6ed9a2ba27bb822f74 < b2f26a27ea3f72f75d18330f76f5d1007c791848b2f26a27ea3f72f75d18330f76f5d1007c791848
linuxlinux>= f88d8ea67fbdbac7a64bfa6ed9a2ba27bb822f74 < 43e25adc80269f917d2a195f0d59f74cdd18295543e25adc80269f917d2a195f0d59f74cdd182955
linuxlinux>= f88d8ea67fbdbac7a64bfa6ed9a2ba27bb822f74 < a3c3f8a4d025acc8c857246ec2b812c59102487aa3c3f8a4d025acc8c857246ec2b812c59102487a
linuxlinux>= f88d8ea67fbdbac7a64bfa6ed9a2ba27bb822f74 < 0e4c6faaef8a24b762a24ffb767280e263ef8e100e4c6faaef8a24b762a24ffb767280e263ef8e10
linuxlinux>= f88d8ea67fbdbac7a64bfa6ed9a2ba27bb822f74 < eb02688c5c45c3e7af7e71f036a7144f5639cbfeeb02688c5c45c3e7af7e71f036a7144f5639cbfe
linuxlinux_kernel>= 0 < 6.1.123-16.1.123-1
linuxlinux_kernel>= 0 < 6.12.3-16.12.3-1
linuxlinux_kernel>= 0 < 6.12.3-16.12.3-1
linuxlinux_kernel>= 0 < 5.15.0-144.1575.15.0-144.157
linuxlinux_kernel>= 0 < 6.8.0-58.606.8.0-58.60
linuxlinux_kernel>= 0 < 6.11.0-18.186.11.0-18.18
linuxlinux_kernel>= 5.3 < 6.1.1206.1.120
linuxlinux_kernel>= 6.12 < 6.12.26.12.2
linuxlinux_kernel>= 6.2 < 6.6.646.6.64
linuxlinux_kernel>= 6.7 < 6.11.116.11.11
msrcazl3_kernel_6.6.57.1-7_on_azure_linux_3.0
msrcazl3_kernel_6.6.64.2-1_on_azure_linux_3.0
msrccbl2_kernel_5.15.182.1-1_on_cbl_mariner_2.0

CVSS provenance

nvdv3.15.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
osv8.8HIGH
vendor_ubuntu8.8HIGH
vendor_debian5.5MEDIUM
vendor_msrc5.5MEDIUM
vendor_redhat5.5MEDIUM
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