CVE-2021-47515 (GCVE-0-2021-47515)
Vulnerability from cvelistv5
Published
2024-05-24 15:09
Modified
2026-05-23 15:20
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: seg6: fix the iif in the IPv6 socket control block When an IPv4 packet is received, the ip_rcv_core(...) sets the receiving interface index into the IPv4 socket control block (v5.16-rc4, net/ipv4/ip_input.c line 510): IPCB(skb)->iif = skb->skb_iif; If that IPv4 packet is meant to be encapsulated in an outer IPv6+SRH header, the seg6_do_srh_encap(...) performs the required encapsulation. In this case, the seg6_do_srh_encap function clears the IPv6 socket control block (v5.16-rc4 net/ipv6/seg6_iptunnel.c line 163): memset(IP6CB(skb), 0, sizeof(*IP6CB(skb))); The memset(...) was introduced in commit ef489749aae5 ("ipv6: sr: clear IP6CB(skb) on SRH ip4ip6 encapsulation") a long time ago (2019-01-29). Since the IPv6 socket control block and the IPv4 socket control block share the same memory area (skb->cb), the receiving interface index info is lost (IP6CB(skb)->iif is set to zero). As a side effect, that condition triggers a NULL pointer dereference if commit 0857d6f8c759 ("ipv6: When forwarding count rx stats on the orig netdev") is applied. To fix that issue, we set the IP6CB(skb)->iif with the index of the receiving interface once again.
References
Impacted products
Vendor Product Version
Linux Linux Version: c630ec8bdadae9d557b1ceb9d6c06e149108a0d4
Version: 2f704348c93ff8119e642dae6a72327f90b82810
Version: ef489749aae508e6f17886775c075f12ff919fb1
Version: ef489749aae508e6f17886775c075f12ff919fb1
Version: ef489749aae508e6f17886775c075f12ff919fb1
Version: ef489749aae508e6f17886775c075f12ff919fb1
Version: b71b7e0280f47b4ac633fbfd153423814ea87810
Version: 4.14.98   ≤
Version: 4.19.20   ≤
Version: 4.20.7   ≤
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