CVE-2026-23410

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

apparmor: fix race on rawdata dereference

There is a race condition that leads to a use-after-free situation: because the rawdata inodes are not refcounted, an attacker can start open()ing one of the rawdata files, and at the same time remove the last reference to this rawdata (by removing the corresponding profile, for example), which frees its struct aa_loaddata; as a result, when seq_rawdata_open() is reached, i_private is a dangling pointer and freed memory is accessed.

The rawdata inodes werent refcounted to avoid a circular refcount and were supposed to be held by the profile rawdata reference. However during profile removal there is a window where the vfs and profile destruction race, resulting in the use after free.

Fix this by moving to a double refcount scheme. Where the profile refcount on rawdata is used to break the circular dependency. Allowing for freeing of the rawdata once all inode references to the rawdata are put.

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/3b8e77c7abab40e6de9ad9de730d77984a498840
• https://git.kernel.org/stable/c/6b6ba87579c7e7c669e0bec91823e7fb693bc5df
• https://git.kernel.org/stable/c/6ef1f2926c41ab96952d9696d55a052f1b3a9418
• https://git.kernel.org/stable/c/763e838adc3c7ec5a7df2990ce84cad951e42721
• https://git.kernel.org/stable/c/a0b7091c4de45a7325c8780e6934a894f92ac86b
• https://git.kernel.org/stable/c/af782cc8871e3683ddd5a3cd2f7df526599863a9
• https://git.kernel.org/stable/c/d9d8560b9b7932f8cffc4c068c14289220900f79
• https://git.kernel.org/stable/c/f9761add6d100962a23996cb68f3d6abdd4d1815