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CVE PROGRAM SOURCE RECORD7.8 High

CVE-2025-38192

net: clear the dst when changing skb protocol

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Status
Published
Published
Updated
Assigning organization
Linux

Description

In the Linux kernel, the following vulnerability has been resolved: net: clear the dst when changing skb protocol A not-so-careful NAT46 BPF program can crash the kernel if it indiscriminately flips ingress packets from v4 to v6: BUG: kernel NULL pointer dereference, address: 0000000000000000 ip6_rcv_core (net/ipv6/ip6_input.c:190:20) ipv6_rcv (net/ipv6/ip6_input.c:306:8) process_backlog (net/core/dev.c:6186:4) napi_poll (net/core/dev.c:6906:9) net_rx_action (net/core/dev.c:7028:13) do_softirq (kernel/softirq.c:462:3) netif_rx (net/core/dev.c:5326:3) dev_loopback_xmit (net/core/dev.c:4015:2) ip_mc_finish_output (net/ipv4/ip_output.c:363:8) NF_HOOK (./include/linux/netfilter.h:314:9) ip_mc_output (net/ipv4/ip_output.c:400:5) dst_output (./include/net/dst.h:459:9) ip_local_out (net/ipv4/ip_output.c:130:9) ip_send_skb (net/ipv4/ip_output.c:1496:8) udp_send_skb (net/ipv4/udp.c:1040:8) udp_sendmsg (net/ipv4/udp.c:1328:10) The output interface has a 4->6 program attached at ingress. We try to loop the multicast skb back to the sending socket. Ingress BPF runs as part of netif_rx(), pushes a valid v6 hdr and changes skb->protocol to v6. We enter ip6_rcv_core which tries to use skb_dst(). But the dst is still an IPv4 one left after IPv4 mcast output. Clear the dst in all BPF helpers which change the protocol. Try to preserve metadata dsts, those may carry non-routing metadata.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Linux Linux

Default version status: unaffected

  • 6578171a7ff0c31dc73258f93da7407510abf085 to < a046f183d21ab5ace5a96ece4cf9873a42f003a7affected
  • 6578171a7ff0c31dc73258f93da7407510abf085 to < 98b1d8dc9a3170b2614f1e8c93854e75cdd83980affected
  • 6578171a7ff0c31dc73258f93da7407510abf085 to < bfa4d86e130a09f67607482e988313430e38f6c4affected
  • 6578171a7ff0c31dc73258f93da7407510abf085 to < 2a3ad42a57b43145839f2f233fb562247658a6d9affected
  • 6578171a7ff0c31dc73258f93da7407510abf085 to < e9994e7b9f7bbb882d13c8191731649249150d21affected
  • 6578171a7ff0c31dc73258f93da7407510abf085 to < ba9db6f907ac02215e30128770f85fbd7db2fcf9affected

Linux Linux

Default version status: affected

  • 4.8affected
  • 0 to < 4.8unaffected
  • 5.15.209 to ≤ 5.15.*unaffected
  • 6.1.167 to ≤ 6.1.*unaffected
  • 6.6.95 to ≤ 6.6.*unaffected
  • 6.12.35 to ≤ 6.12.*unaffected
  • 6.15.4 to ≤ 6.15.*unaffected
  • 6.16 to ≤ *unaffected

References