CVE-2026-68273

In the Linux kernel, the following vulnerability has been resolved:

drm/amdgpu: Fix context pstate override handling

There are several problems in the context pstate handling code.

The most serious ones are potential use-after-free and NULL pointer dereferences at context initialization time. Both are due amdgpu_ctx_init() not holding the adev->pm.stable_pstate_ctx_lock, which is otherwise used from both sysfs and the context code itself for modifying and clearing the stored context pointer.

Second issue is that context fini can trample over the pstate configuration set via sysfs. This is due the restore state (ctx->stable_pstate) being saved at context init time, and not if, or when the context actually changes the pstate. As the context exits it will therefore incorrectly restore to what was set before the sysfs override was requested.

The simplest fix is to drastically simplify how the state is tracked, by clearly defining the points at which pstate ownership is taken and released, and to handle all transitions under the correct lock.

Instead of at context init time, the previous state is saved only at the point the context overrides the current state, and is restored on context exit only if the context is still the owner of the current override state.

(cherry picked from commit 1b5e413713c0a93bc1818394d0ce49aaad21bd27)

Weakness

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.

Affected Software

Extended Description

A race condition occurs within concurrent environments, and it is effectively a property of a code sequence. Depending on the context, a code sequence may be in the form of a function call, a small number of instructions, a series of program invocations, etc. A race condition violates these properties, which are closely related:

A race condition exists when an “interfering code sequence” can still access the shared resource, violating exclusivity. The interfering code sequence could be “trusted” or “untrusted.” A trusted interfering code sequence occurs within the product; it cannot be modified by the attacker, and it can only be invoked indirectly. An untrusted interfering code sequence can be authored directly by the attacker, and typically it is external to the vulnerable product.

Potential Mitigations

• Minimize the usage of shared resources in order to remove as much complexity as possible from the control flow and to reduce the likelihood of unexpected conditions occurring.
• Additionally, this will minimize the amount of synchronization necessary and may even help to reduce the likelihood of a denial of service where an attacker may be able to repeatedly trigger a critical section (CWE-400).

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/26.html
• https://cwe.mitre.org/data/definitions/29.html

References

• https://git.kernel.org/stable/c/23a8726e1d7597fe7c9a59d5dc42ba8b7d345b8a
• https://git.kernel.org/stable/c/3531910845165dcf1a213267199ccc97e03cd58a
• https://git.kernel.org/stable/c/9f9c88eb298c54348be3ca4087f4f4c615065b87
• https://git.kernel.org/stable/c/c1dc4ccb82c9e56325d8e7514ca4c90bd1efb351
• https://git.kernel.org/stable/c/e06c39cc1c48dca68a5ffd971c23025a52d46634
• https://git.kernel.org/stable/c/ebed6179c993f07da24d0a454816e7da790377af