ppp: fix race conditions in ppp_fill_forward_path

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Summary

CVECVE-2025-39673
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2025-09-05 18:15:43 UTC
Updated2026-05-12 13:17:03 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: ppp: fix race conditions in ppp_fill_forward_path ppp_fill_forward_path() has two race conditions: 1. The ppp->channels list can change between list_empty() and list_first_entry(), as ppp_lock() is not held. If the only channel is deleted in ppp_disconnect_channel(), list_first_entry() may access an empty head or a freed entry, and trigger a panic. 2. pch->chan can be NULL. When ppp_unregister_channel() is called, pch->chan is set to NULL before pch is removed from ppp->channels. Fix these by using a lockless RCU approach: - Use list_first_or_null_rcu() to safely test and access the first list entry. - Convert list modifications on ppp->channels to their RCU variants and add synchronize_net() after removal. - Check for a NULL pch->chan before dereferencing it.

Risk And Classification

Primary CVSS: v3.1 4.7 MEDIUM from [email protected]

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

Problem Types: CWE-362

CVSS v3.1 Breakdown

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

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

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Linux Linux Kernel All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected f6efc675c9dd8d93f826b79ae7e33e03301db609 9a1969fbffc1f1900d92d7594b1b7d8d72ef3dc7 git Not specified
CNA Linux Linux affected f6efc675c9dd8d93f826b79ae7e33e03301db609 0f1630be6fcca3f0c63e4b242ad202e5cde28a40 git Not specified
CNA Linux Linux affected f6efc675c9dd8d93f826b79ae7e33e03301db609 ca18d751bcc9faf5b7e82e9fae1223d103928181 git Not specified
CNA Linux Linux affected f6efc675c9dd8d93f826b79ae7e33e03301db609 94731cc551e29511d85aa8dec61a6c071b1f2430 git Not specified
CNA Linux Linux affected f6efc675c9dd8d93f826b79ae7e33e03301db609 f97f6475fdcb3c28ff3c55cc4b7bde632119ec08 git Not specified
CNA Linux Linux affected f6efc675c9dd8d93f826b79ae7e33e03301db609 0417adf367a0af11adf7ace849af4638cfb573f7 git Not specified
CNA Linux Linux affected 5.13 Not specified
CNA Linux Linux unaffected 5.13 semver Not specified
CNA Linux Linux unaffected 5.15.190 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.149 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.103 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.44 6.12.* semver Not specified
CNA Linux Linux unaffected 6.16.4 6.16.* semver Not specified
CNA Linux Linux unaffected 6.17 * original_commit_for_fix Not specified
ADP Siemens SIMATIC CN 4100 affected V5.0 custom Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/ca18d751bcc9faf5b7e82e9fae1223d103928181 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
lists.debian.org/debian-lts-announce/2025/10/msg00008.html af854a3a-2127-422b-91ae-364da2661108 lists.debian.org Third Party Advisory
git.kernel.org/stable/c/0f1630be6fcca3f0c63e4b242ad202e5cde28a40 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
cert-portal.siemens.com/productcert/html/ssa-032379.html 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e cert-portal.siemens.com
git.kernel.org/stable/c/9a1969fbffc1f1900d92d7594b1b7d8d72ef3dc7 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/0417adf367a0af11adf7ace849af4638cfb573f7 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/94731cc551e29511d85aa8dec61a6c071b1f2430 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/f97f6475fdcb3c28ff3c55cc4b7bde632119ec08 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
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