{"id":"CVE-2021-47515","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nseg6: fix the iif in the IPv6 socket control block\n\nWhen an IPv4 packet is received, the ip_rcv_core(...) sets the receiving\ninterface index into the IPv4 socket control block (v5.16-rc4,\nnet/ipv4/ip_input.c line 510):\n\n    IPCB(skb)-\u003eiif = skb-\u003eskb_iif;\n\nIf that IPv4 packet is meant to be encapsulated in an outer IPv6+SRH\nheader, the seg6_do_srh_encap(...) performs the required encapsulation.\nIn this case, the seg6_do_srh_encap function clears the IPv6 socket control\nblock (v5.16-rc4 net/ipv6/seg6_iptunnel.c line 163):\n\n    memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));\n\nThe memset(...) was introduced in commit ef489749aae5 (\"ipv6: sr: clear\nIP6CB(skb) on SRH ip4ip6 encapsulation\") a long time ago (2019-01-29).\n\nSince the IPv6 socket control block and the IPv4 socket control block share\nthe same memory area (skb-\u003ecb), the receiving interface index info is lost\n(IP6CB(skb)-\u003eiif is set to zero).\n\nAs a side effect, that condition triggers a NULL pointer dereference if\ncommit 0857d6f8c759 (\"ipv6: When forwarding count rx stats on the orig\nnetdev\") is applied.\n\nTo fix that issue, we set the IP6CB(skb)-\u003eiif with the index of the\nreceiving interface once again.","modified":"2026-03-15T21:45:04.951591Z","published":"2024-05-24T15:15:12.937Z","related":["SUSE-SU-2024:2372-1","SUSE-SU-2024:2394-1","SUSE-SU-2024:2939-1"],"references":[{"type":"FIX","url":"https://git.kernel.org/stable/c/ae68d93354e5bf5191ee673982251864ea24dd5c"},{"type":"FIX","url":"https://git.kernel.org/stable/c/b16d412e5f79734033df04e97d7ea2f50a8e9fe3"},{"type":"FIX","url":"https://git.kernel.org/stable/c/ef8804e47c0a44ae106ead1740408af5ea6c6ee9"},{"type":"FIX","url":"https://git.kernel.org/stable/c/6431e71093f3da586a00c6d931481ffb0dc2db0e"},{"type":"FIX","url":"https://git.kernel.org/stable/c/666521b3852d2b2f52d570f9122b1e4b50d96831"},{"type":"FIX","url":"https://git.kernel.org/stable/c/98adb2bbfa407c9290bda299d4c6f7a1c4ebd5e1"}],"affected":[{"database_specific":{"unresolved_ranges":[{"events":[{"introduced":"4.14.98"},{"fixed":"4.14.258"}]},{"events":[{"introduced":"4.19.20"},{"fixed":"4.19.221"}]},{"events":[{"introduced":"4.20.7"},{"fixed":"5.0"}]},{"events":[{"introduced":"5.0.1"},{"fixed":"5.4.165"}]},{"events":[{"introduced":"5.5"},{"fixed":"5.10.85"}]},{"events":[{"introduced":"5.11"},{"fixed":"5.15.8"}]},{"events":[{"introduced":"0"},{"last_affected":"5.0-NA"}]},{"events":[{"introduced":"0"},{"last_affected":"5.0-rc6"}]},{"events":[{"introduced":"0"},{"last_affected":"5.0-rc7"}]},{"events":[{"introduced":"0"},{"last_affected":"5.0-rc8"}]},{"events":[{"introduced":"0"},{"last_affected":"5.16-rc1"}]},{"events":[{"introduced":"0"},{"last_affected":"5.16-rc2"}]},{"events":[{"introduced":"0"},{"last_affected":"5.16-rc3"}]},{"events":[{"introduced":"0"},{"last_affected":"5.16-rc4"}]}],"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-47515.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"}]}