[ciqlts8_6] ipv6: icmp: clear skb2->cb[] in ip6_err_gen_icmpv6_unreach()#1331
Merged
Conversation
jira VULN-183735 cve CVE-2026-43038 commit-author Eric Dumazet <edumazet@google.com> commit 86ab3e5 Sashiko AI-review observed: In ip6_err_gen_icmpv6_unreach(), the skb is an outer IPv4 ICMP error packet where its cb contains an IPv4 inet_skb_parm. When skb is cloned into skb2 and passed to icmp6_send(), it uses IP6CB(skb2). IP6CB interprets the IPv4 inet_skb_parm as an inet6_skb_parm. The cipso offset in inet_skb_parm.opt directly overlaps with dsthao in inet6_skb_parm at offset 18. If an attacker sends a forged ICMPv4 error with a CIPSO IP option, dsthao would be a non-zero offset. Inside icmp6_send(), mip6_addr_swap() is called and uses ipv6_find_tlv(skb, opt->dsthao, IPV6_TLV_HAO). This would scan the inner, attacker-controlled IPv6 packet starting at that offset, potentially returning a fake TLV without checking if the remaining packet length can hold the full 18-byte struct ipv6_destopt_hao. Could mip6_addr_swap() then perform a 16-byte swap that extends past the end of the packet data into skb_shared_info? Should the cb array also be cleared in ip6_err_gen_icmpv6_unreach() and ip6ip6_err() to prevent this? This patch implements the first suggestion. I am not sure if ip6ip6_err() needs to be changed. A separate patch would be better anyway. Fixes: ca15a07 ("sit: generate icmpv6 error when receiving icmpv4 error") Reported-by: Ido Schimmel <idosch@nvidia.com> Closes: https://sashiko.dev/#/patchset/20260326155138.2429480-1-edumazet%40google.com Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Oskar Kjos <oskar.kjos@hotmail.com> Reviewed-by: Ido Schimmel <idosch@nvidia.com> Link: https://patch.msgid.link/20260326202608.2976021-1-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> (cherry picked from commit 86ab3e5) Signed-off-by: Brett Mastbergen <bmastbergen@ciq.com>
jira VULN-183729 cve CVE-2026-43037 commit-author Eric Dumazet <edumazet@google.com> commit 2edfa31 Oskar Kjos reported the following problem. ip4ip6_err() calls icmp_send() on a cloned skb whose cb[] was written by the IPv6 receive path as struct inet6_skb_parm. icmp_send() passes IPCB(skb2) to __ip_options_echo(), which interprets that cb[] region as struct inet_skb_parm (IPv4). The layouts differ: inet6_skb_parm.nhoff at offset 14 overlaps inet_skb_parm.opt.rr, producing a non-zero rr value. __ip_options_echo() then reads optlen from attacker-controlled packet data at sptr[rr+1] and copies that many bytes into dopt->__data, a fixed 40-byte stack buffer (IP_OPTIONS_DATA_FIXED_SIZE). To fix this we clear skb2->cb[], as suggested by Oskar Kjos. Also add minimal IPv4 header validation (version == 4, ihl >= 5). Fixes: c4d3efa ("[IPV6] IP6TUNNEL: Add support to IPv4 over IPv6 tunnel.") Reported-by: Oskar Kjos <oskar.kjos@hotmail.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Ido Schimmel <idosch@nvidia.com> Link: https://patch.msgid.link/20260326155138.2429480-1-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> (cherry picked from commit 2edfa31) Signed-off-by: Brett Mastbergen <bmastbergen@ciq.com>
ciq-kernel-automation
Bot
added
the
created-by-kernelci
|
🤖 Validation Checks In Progress Workflow run: https://github.com/ctrliq/kernel-src-tree/actions/runs/27364966796 |
|
✅ Validation checks completed successfully View full results: https://github.com/ctrliq/kernel-src-tree/actions/runs/27364966796 |
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Summary
This PR has been automatically created after successful completion of all CI stages.
Commit Message(s)
Test Results
✅ Build Stage
✅ Boot Verification
✅ Kernel Selftests
✅ LTP Results
🤖 This PR was automatically generated by GitHub Actions
Run ID: 27349835285