cbcvebase.
CVE-2024-27415
published 2024-05-17

CVE-2024-27415: In the Linux kernel, the following vulnerability has been resolved: netfilter: bridge: confirm multicast packets before passing them up the stack conntrack…

PriorityP418medium4.7CVSS 3.1
AVLACHPRLUINSUCNINAH
EPSS
0.24%
15.7th percentile
In the Linux kernel, the following vulnerability has been resolved: netfilter: bridge: confirm multicast packets before passing them up the stack conntrack nf_confirm logic cannot handle cloned skbs referencing the same nf_conn entry, which will happen for multicast (broadcast) frames on bridges. Example: macvlan0 | br0 / \ ethX ethY ethX (or Y) receives a L2 multicast or broadcast packet containing an IP packet, flow is not yet in conntrack table. 1. skb passes through bridge and fake-ip (br_netfilter)Prerouting. -> skb->_nfct now references a unconfirmed entry 2. skb is broad/mcast packet. bridge now passes clones out on each bridge interface. 3. skb gets passed up the stack. 4. In macvlan case, macvlan driver retains clone(s) of the mcast skb and schedules a work queue to send them out on the lower devices. The clone skb->_nfct is not a copy, it is the same entry as the original skb. The macvlan rx handler then returns RX_HANDLER_PASS. 5. Normal conntrack hooks (in NF_INET_LOCAL_IN) confirm the orig skb. The Macvlan broadcast worker and normal confirm path will race. This race will not happen if step 2 already confirmed a clone. In that case later steps perform skb_clone() with skb->_nfct already confirmed (in hash table). This works fine. But such confirmation won't happen when eb/ip/nftables rules dropped the packets before they reached the nf_confirm step in postrouting. Pablo points out that nf_conntrack_bridge doesn't allow use of stateful nat, so we can safely discard the nf_conn entry and let inet call conntrack again. This doesn't work for bridge netfilter: skb could have a nat transformation. Also bridge nf prevents re-invocation of inet prerouting via 'sabotage_in' hook. Work around this problem by explicit confirmation of the entry at LOCAL_IN time, before upper layer has a chance to clone the unconfirmed entry. The downside is that this disables NAT and conntrack helpers. Alternative fix would be to add locking to all code parts that dea

Affected

26 ranges· showing 25
VendorProductVersion rangeFixed in
debianlinux< linux 6.1.82-1 (bookworm)linux 6.1.82-1 (bookworm)
linuxlinux
linuxlinux>= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 7c3f28599652acf431a2211168de4a583f30b6d57c3f28599652acf431a2211168de4a583f30b6d5
linuxlinux>= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 2b1414d5e94e477edff1d2c79030f1d742625ea02b1414d5e94e477edff1d2c79030f1d742625ea0
linuxlinux>= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 80cd0487f630b5382734997c3e5e3003a77db31580cd0487f630b5382734997c3e5e3003a77db315
linuxlinux>= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < cb734975b0ffa688ff6cc0eed463865bf07b6c01cb734975b0ffa688ff6cc0eed463865bf07b6c01
linuxlinux>= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 62e7151ae3eb465e0ab52a20c941ff33bb6332e962e7151ae3eb465e0ab52a20c941ff33bb6332e9
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel>= 0 < 6.1.82-16.1.82-1
linuxlinux_kernel>= 0 < 6.7.9-16.7.9-1
linuxlinux_kernel>= 0 < 6.7.9-16.7.9-1
linuxlinux_kernel>= 0 < 5.15.0-112.1225.15.0-112.122
linuxlinux_kernel>= 2.6.13 < 5.15.1515.15.151
linuxlinux_kernel>= 5.16 < 6.1.816.1.81
linuxlinux_kernel>= 6.2 < 6.6.216.6.21

CVSS provenance

nvdv3.14.7MEDIUMCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
osv7.0HIGH
vendor_ubuntu7.0HIGH
vendor_debian4.7MEDIUM
vendor_redhat4.7MEDIUM
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