CVE-2025-39905 (GCVE-0-2025-39905)

Vulnerability from cvelistv5 – Published: 2025-10-01 07:44 – Updated: 2026-01-14 19:33
VLAI?
Title
net: phylink: add lock for serializing concurrent pl->phydev writes with resolver
Summary
In the Linux kernel, the following vulnerability has been resolved: net: phylink: add lock for serializing concurrent pl->phydev writes with resolver Currently phylink_resolve() protects itself against concurrent phylink_bringup_phy() or phylink_disconnect_phy() calls which modify pl->phydev by relying on pl->state_mutex. The problem is that in phylink_resolve(), pl->state_mutex is in a lock inversion state with pl->phydev->lock. So pl->phydev->lock needs to be acquired prior to pl->state_mutex. But that requires dereferencing pl->phydev in the first place, and without pl->state_mutex, that is racy. Hence the reason for the extra lock. Currently it is redundant, but it will serve a functional purpose once mutex_lock(&phy->lock) will be moved outside of the mutex_lock(&pl->state_mutex) section. Another alternative considered would have been to let phylink_resolve() acquire the rtnl_mutex, which is also held when phylink_bringup_phy() and phylink_disconnect_phy() are called. But since phylink_disconnect_phy() runs under rtnl_lock(), it would deadlock with phylink_resolve() when calling flush_work(&pl->resolve). Additionally, it would have been undesirable because it would have unnecessarily blocked many other call paths as well in the entire kernel, so the smaller-scoped lock was preferred.
Severity ?
7 (High)
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE
  • CWE-362 - Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 5fd0f1a02e750e2db4038dee60edea669ce5aab1 , < 56fe63b05ec84ae6674269d78397cec43a7a295a (git)
Affected: 5fd0f1a02e750e2db4038dee60edea669ce5aab1 , < 0ba5b2f2c381dbec9ed9e4ab3ae5d3e667de0dc3 (git)
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    Linux Linux Affected: 6.14
Unaffected: 0 , < 6.14 (semver)
Unaffected: 6.16.8 , ≤ 6.16.* (semver)
Unaffected: 6.17 , ≤ * (original_commit_for_fix)
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Sightings

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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



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