fkie_cve-2025-39905
Vulnerability from fkie_nvd
Published
2025-10-01 08:15
Modified
2025-10-02 19:12
Severity ?
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.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/0ba5b2f2c381dbec9ed9e4ab3ae5d3e667de0dc3
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/56fe63b05ec84ae6674269d78397cec43a7a295a
Impacted products
Vendor Product Version


To clipboard 

{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: phylink: add lock for serializing concurrent pl-\u003ephydev writes with resolver\n\nCurrently phylink_resolve() protects itself against concurrent\nphylink_bringup_phy() or phylink_disconnect_phy() calls which modify\npl-\u003ephydev by relying on pl-\u003estate_mutex.\n\nThe problem is that in phylink_resolve(), pl-\u003estate_mutex is in a lock\ninversion state with pl-\u003ephydev-\u003elock. So pl-\u003ephydev-\u003elock needs to be\nacquired prior to pl-\u003estate_mutex. But that requires dereferencing\npl-\u003ephydev in the first place, and without pl-\u003estate_mutex, that is\nracy.\n\nHence the reason for the extra lock. Currently it is redundant, but it\nwill serve a functional purpose once mutex_lock(\u0026phy-\u003elock) will be\nmoved outside of the mutex_lock(\u0026pl-\u003estate_mutex) section.\n\nAnother alternative considered would have been to let phylink_resolve()\nacquire the rtnl_mutex, which is also held when phylink_bringup_phy()\nand phylink_disconnect_phy() are called. But since phylink_disconnect_phy()\nruns under rtnl_lock(), it would deadlock with phylink_resolve() when\ncalling flush_work(\u0026pl-\u003eresolve). Additionally, it would have been\nundesirable because it would have unnecessarily blocked many other call\npaths as well in the entire kernel, so the smaller-scoped lock was\npreferred."
    }
  ],
  "id": "CVE-2025-39905",
  "lastModified": "2025-10-02T19:12:17.160",
  "metrics": {},
  "published": "2025-10-01T08:15:33.370",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/0ba5b2f2c381dbec9ed9e4ab3ae5d3e667de0dc3"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/56fe63b05ec84ae6674269d78397cec43a7a295a"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Awaiting Analysis"
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
  • Confirmed: The vulnerability is confirmed from an analyst perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
  • Patched: This vulnerability was successfully patched by the user reporting the sighting.
  • Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
  • Not confirmed: The user expresses doubt about the veracity of the vulnerability.
  • Not patched: This vulnerability was not successfully patched by the user reporting the sighting.