net: thunderbolt: Tear down DMA paths before stopping the rings

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-74691
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-22 16:16:43 UTC
Updated2026-08-25 06:18:52 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: net: thunderbolt: Tear down DMA paths before stopping the rings tbnet_tear_down() stops both rings and frees their frame buffers before calling tb_xdomain_disable_paths(). tb_ring_stop() zeroes the ring's descriptor base and tbnet_free_buffers() unmaps and frees the pages the frames sit in, so by the time __tb_path_deactivate_hop() polls the hop's 'pending' bit, anything still in flight has nowhere to drain to. The teardown sequence has been in this order since the driver was added. The setup path has not: commit ff7cd07f3064 ("net: thunderbolt: Enable DMA paths only after rings are enabled") moved the path enable to the end of tbnet_connected_work() and documented why: /* Both logins successful so enable the rings, high-speed DMA * paths and start the network device queue. * * Note we enable the DMA paths last to make sure we have primed * the Rx ring before any incoming packets are allowed to * arrive. */ Teardown was never updated to match, so the rings and the paths now come down in the same order they go up instead of in reverse. On an ASMedia ASM4242 host router the 'pending' bit then never clears: every teardown burns the full 500 ms timeout and __tb_path_deactivate_hop() returns -ETIMEDOUT. Raising the timeout to 5 s does not help, so the hop is not slow to drain, it never drains at all. The failure is invisible above the thunderbolt core. __tb_path_deactivate_hops() is void and only calls tb_port_warn(); tb_path_deactivate(), tb_tunnel_deactivate() and __tb_disconnect_xdomain_paths() are void as well, and tb_disconnect_xdomain_paths() ends in an unconditional "return 0". So tb_xdomain_disable_paths() reports success and the netdev_warn() below it never fires. Repeated teardowns eventually take the XDomain control channel down, after which the peer node is gone and only a power cycle brings the controller back. Deactivating the paths first fixes it. Measured with kretprobes on a stock v6.17 tree with no other patches applied, on a link that was up and had just carried traffic: before: __tb_path_deactivate_hop() returns 0 for the first hop, then -ETIMEDOUT for the second 500335 us later after: 0 for both, 525 us apart Alternating the two orderings ABBA over three load levels, four teardowns per arm: every teardown failed before the change (21 of 21 that ran), none failed after (0 of 24). The before arms ran short because the link died partway through. The same split shows up when the interface is enslaved to a bond instead of just brought down, which is how I ran into this in the first place. Throughput and latency after the change are unchanged. Hosts whose routers drain the hop despite the stale descriptor base see no functional difference, since the paths end up deactivated either way.

Risk And Classification

Primary CVSS: v3.1 8.8 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

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

EPSS: 0.002560000 probability, percentile 0.169310000 (date 2026-08-25)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary8.8HIGHCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED8.8HIGHCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

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

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected e69b6c02b4c3b8d03be7136f90dd9551ad5a5a5e 7cce39109206bc5497e0953806563644b88bfc44 git Not specified
CNA Linux Linux affected e69b6c02b4c3b8d03be7136f90dd9551ad5a5a5e 0da9a6d27155ad072dd76db8cd637feead99a0e0 git Not specified
CNA Linux Linux affected e69b6c02b4c3b8d03be7136f90dd9551ad5a5a5e b5a21615f627c48dafaa6ef82a34a5b97a4352aa git Not specified
CNA Linux Linux affected e69b6c02b4c3b8d03be7136f90dd9551ad5a5a5e 103a9b663ac1cacb8465aeff18f84a247154a562 git Not specified
CNA Linux Linux affected e69b6c02b4c3b8d03be7136f90dd9551ad5a5a5e 4dd71cb0d23d40cb58fe4261c7bd183dca66caa0 git Not specified
CNA Linux Linux affected e69b6c02b4c3b8d03be7136f90dd9551ad5a5a5e 9a482b2b117e5fa656b6d24fc01799e8ac2d4368 git Not specified
CNA Linux Linux affected e69b6c02b4c3b8d03be7136f90dd9551ad5a5a5e 68bf02b6b4ad3f748c6db71fd77b6c0402d252f4 git Not specified
CNA Linux Linux affected 4.15 Not specified
CNA Linux Linux unaffected 4.15 semver Not specified
CNA Linux Linux unaffected 5.15.216 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.183 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.152 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.104 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.45 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.9 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/4dd71cb0d23d40cb58fe4261c7bd183dca66caa0 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/7cce39109206bc5497e0953806563644b88bfc44 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/9a482b2b117e5fa656b6d24fc01799e8ac2d4368 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/68bf02b6b4ad3f748c6db71fd77b6c0402d252f4 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/0da9a6d27155ad072dd76db8cd637feead99a0e0 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/b5a21615f627c48dafaa6ef82a34a5b97a4352aa 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/103a9b663ac1cacb8465aeff18f84a247154a562 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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