CVE-2024-26810

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

vfio/pci: Lock external INTx masking ops

Mask operations through config space changes to DisINTx may race INTx configuration changes via ioctl. Create wrappers that add locking for paths outside of the core interrupt code.

In particular, irq_type is updated holding igate, therefore testing is_intx() requires holding igate. For example clearing DisINTx from config space can otherwise race changes of the interrupt configuration.

This aligns interfaces which may trigger the INTx eventfd into two camps, one side serialized by igate and the other only enabled while INTx is configured. A subsequent patch introduces synchronization for the latter flows.

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/03505e3344b0576fd619416793a31eae9c5b73bf
• https://git.kernel.org/stable/c/04a4a017b9ffd7b0f427b8c376688d14cb614651
• https://git.kernel.org/stable/c/1e71b6449d55179170efc8dee8664510bb813b42
• https://git.kernel.org/stable/c/3dd9be6cb55e0f47544e7cdda486413f7134e3b3
• https://git.kernel.org/stable/c/3fe0ac10bd117df847c93408a9d428a453cd60e5
• https://git.kernel.org/stable/c/6fe478d855b20ac1eb5da724afe16af5a2aaaa40
• https://git.kernel.org/stable/c/810cd4bb53456d0503cc4e7934e063835152c1b7
• https://git.kernel.org/stable/c/ec73e079729258a05452356cf6d098bf1504d5a6
• https://git.kernel.org/stable/c/03505e3344b0576fd619416793a31eae9c5b73bf
• https://git.kernel.org/stable/c/04a4a017b9ffd7b0f427b8c376688d14cb614651
• https://git.kernel.org/stable/c/1e71b6449d55179170efc8dee8664510bb813b42
• https://git.kernel.org/stable/c/3dd9be6cb55e0f47544e7cdda486413f7134e3b3
• https://git.kernel.org/stable/c/3fe0ac10bd117df847c93408a9d428a453cd60e5
• https://git.kernel.org/stable/c/6fe478d855b20ac1eb5da724afe16af5a2aaaa40
• https://git.kernel.org/stable/c/810cd4bb53456d0503cc4e7934e063835152c1b7
• https://git.kernel.org/stable/c/ec73e079729258a05452356cf6d098bf1504d5a6
• https://lists.debian.org/debian-lts-announce/2024/06/msg00017.html