Bug 2463259 (CVE-2026-31688)

Summary: CVE-2026-31688 kernel: driver core: enforce device_lock for driver_match_device()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's driver core. An inconsistency in enforcing the `device_lock` for `driver_match_device()` can lead to a race condition. This issue, specifically when the `driver_override` implementation is used, can result in a use-after-free (UAF) vulnerability. A use-after-free vulnerability occurs when a program attempts to use memory after it has been freed, which can lead to system instability or potentially arbitrary code execution.
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Description OSIDB Bzimport 2026-04-27 18:23:52 UTC 
In the Linux kernel, the following vulnerability has been resolved:

driver core: enforce device_lock for driver_match_device()

Currently, driver_match_device() is called from three sites. One site
(__device_attach_driver) holds device_lock(dev), but the other two
(bind_store and __driver_attach) do not. This inconsistency means that
bus match() callbacks are not guaranteed to be called with the lock
held.

Fix this by introducing driver_match_device_locked(), which guarantees
holding the device lock using a scoped guard. Replace the unlocked calls
in bind_store() and __driver_attach() with this new helper. Also add a
lock assertion to driver_match_device() to enforce this guarantee.

This consistency also fixes a known race condition. The driver_override
implementation relies on the device_lock, so the missing lock led to the
use-after-free (UAF) reported in Bugzilla for buses using this field.

Stress testing the two newly locked paths for 24 hours with
CONFIG_PROVE_LOCKING and CONFIG_LOCKDEP enabled showed no UAF recurrence
and no lockdep warnings.
Comment 1 Keith Grant 2026-04-27 22:15:34 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026042706-CVE-2026-31688-1f56@gregkh/T