CVE-2024-27009

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

s390/cio: fix race condition during online processing

A race condition exists in ccw_device_set_online() that can cause the online process to fail, leaving the affected device in an inconsistent state. As a result, subsequent attempts to set that device online fail with return code ENODEV.

The problem occurs when a path verification request arrives after a wait for final device state completed, but before the result state is evaluated.

Fix this by ensuring that the CCW-device lock is held between determining final state and checking result state.

Note that since:

commit 2297791c92d0 (s390/cio: dont unregister subchannel from child-drivers)

path verification requests are much more likely to occur during boot, resulting in an increased chance of this race condition occurring.

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/2d8527f2f911fab84aec04df4788c0c23af3df48
• https://git.kernel.org/stable/c/2df56f4ea769ff81e51bbb05699989603bde9c49
• https://git.kernel.org/stable/c/3076b3c38a704e10df5e143c213653309d532538
• https://git.kernel.org/stable/c/559f3a6333397ab6cd4a696edd65a70b6be62c6e
• https://git.kernel.org/stable/c/a4234decd0fe429832ca81c4637be7248b88b49e
• https://git.kernel.org/stable/c/2d8527f2f911fab84aec04df4788c0c23af3df48
• https://git.kernel.org/stable/c/2df56f4ea769ff81e51bbb05699989603bde9c49
• https://git.kernel.org/stable/c/3076b3c38a704e10df5e143c213653309d532538
• https://git.kernel.org/stable/c/559f3a6333397ab6cd4a696edd65a70b6be62c6e
• https://git.kernel.org/stable/c/a4234decd0fe429832ca81c4637be7248b88b49e
• https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/4EZ6PJW7VOZ224TD7N4JZNU6KV32ZJ53/
• https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/DAMSOZXJEPUOXW33WZYWCVAY7Z5S7OOY/
• https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/GCBZZEC7L7KTWWAS2NLJK6SO3IZIL4WW/