net/handshake: Drain pending requests at net namespace exit

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-63978
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-19 16:17:16 UTC
Updated2026-07-20 15:17:00 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: net/handshake: Drain pending requests at net namespace exit The arguments to list_splice_init() in handshake_net_exit() are reversed. The call moves the local empty "requests" list onto hn->hn_requests, leaving the local list empty, so the subsequent drain loop runs zero iterations. Pending handshake requests that had not yet been accepted are not torn down when the net namespace is destroyed; each one keeps a reference on a socket file and on the handshake_req allocation. Pass the source and destination in the documented order (list_splice_init(list, head) moves list onto head) so the pending list is transferred to the local scratch list and drained through handshake_complete(). Fixing the splice direction exposes a list-corruption race. After the splice each req->hr_list still has non-empty link pointers, threading the stack-local scratch list rather than hn_requests. A concurrent handshake_req_cancel() -- for example, from sunrpc's TLS timeout on a kernel socket whose netns reference was not taken -- finds the request through the rhashtable, calls remove_pending(), and sees !list_empty(&req->hr_list). __remove_pending_locked() then list_del_init()s an entry off the scratch list while the drain iterates, corrupting it. The same call arriving after the drain loop has run list_del() on an entry hits LIST_POISON instead. Have remove_pending() check HANDSHAKE_F_NET_DRAINING under hn_lock and report not-found when drain is in progress. The drain has already taken ownership; handshake_complete()'s existing test_and_set on HANDSHAKE_F_REQ_COMPLETED still arbitrates between drain and cancel for who calls the consumer's hp_done. Use list_del_init() rather than list_del() in the drain so req->hr_list does not carry LIST_POISON after drain releases the entry. The DRAINING guard in remove_pending() makes cancel return false, but cancel still falls through to test_and_set_bit on HANDSHAKE_F_REQ_COMPLETED and drops the request's hr_file reference. Without another pin, if that is the last reference, sk_destruct frees the request while it is still linked on the drain loop's local list. Pin each request's hr_file under hn_lock before releasing the list, and drop that drain pin after the loop finishes with the request.

Risk And Classification

Primary CVSS: v3.1 9.8 CRITICAL from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS: 0.001980000 probability, percentile 0.097880000 (date 2026-07-20)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary9.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED9.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 3b3009ea8abb713b022d94fba95ec270cf6e7eae 9ec20c9a5a04f2c3f1cf65d21f886d7aaa6189cd git Not specified
CNA Linux Linux affected 3b3009ea8abb713b022d94fba95ec270cf6e7eae 8c35539db0ab0bfa1ea44efab00b053261a69469 git Not specified
CNA Linux Linux affected 3b3009ea8abb713b022d94fba95ec270cf6e7eae ea5fe6a73ca57e5150b8a38b341aef2636eb72f0 git Not specified
CNA Linux Linux affected 6.4 Not specified
CNA Linux Linux unaffected 6.4 semver Not specified
CNA Linux Linux unaffected 6.12.93 6.12.* semver Not specified
CNA Linux Linux unaffected 7.0.12 7.0.* semver Not specified
CNA Linux Linux unaffected 7.1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/9ec20c9a5a04f2c3f1cf65d21f886d7aaa6189cd 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/8c35539db0ab0bfa1ea44efab00b053261a69469 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/ea5fe6a73ca57e5150b8a38b341aef2636eb72f0 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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