CVE-2025-39905
Unknown
Unknown - Not Provided
BaseFortify
Publication date: 2025-10-01
Last updated on: 2025-12-12
Assigner: kernel.org
Description
Description
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.
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| linux | linux_kernel | to 6.16.8 (exc) |
| linux | linux_kernel | 6.17 |
| linux | linux_kernel | 6.17 |
| linux | linux_kernel | 6.17 |
| linux | linux_kernel | 6.17 |
| linux | linux_kernel | 6.17 |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-362 | The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently. |
