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CVE-2021-47515

seg6: fix the iif in the IPv6 socket control block PUBLISHED

Description (CNA)

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.

Affected (CNA)

Vendor / productVersions
Linux / Linuxaffected c630ec8bdadae9d557b1ceb9d6c06e149108a0d4 before b16d412e5f79734033df04e97d7ea2f50a8e9fe3; affected 2f704348c93ff8119e642dae6a72327f90b82810 before 6431e71093f3da586a00c6d931481ffb0dc2db0e; affected ef489749aae508e6f17886775c075f12ff919fb1 before ef8804e47c0a44ae106ead1740408af5ea6c6ee9; affected ef489749aae508e6f17886775c075f12ff919fb1 before 666521b3852d2b2f52d570f9122b1e4b50d96831; affected ef489749aae508e6f17886775c075f12ff919fb1 before 98adb2bbfa407c9290bda299d4c6f7a1c4ebd5e1; affected ef489749aae508e6f17886775c075f12ff919fb1 before ae68d93354e5bf5191ee673982251864ea24dd5c; affected b71b7e0280f47b4ac633fbfd153423814ea87810; affected 4.14.98 before 4.14.258; affected 4.19.20 before 4.19.221; affected 4.20.7 before 4.21
Linux / Linuxaffected 5.0; unaffected 0 before 5.0; unaffected 4.14.258 through 4.14.*; unaffected 4.19.221 through 4.19.*; unaffected 5.4.165 through 5.4.*; unaffected 5.10.85 through 5.10.*; unaffected 5.15.8 through 5.15.*; unaffected 5.16 through *

CWE

No CWE identifiers supplied.

References

ADP enrichment

CVE

No English description supplied.

CISA-ADP

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No references supplied.