CVE-2026-63945

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

Bluetooth: ISO: serialize iso_sock_clear_timer with socket lock

iso_sock_close() calls iso_sock_clear_timer() before acquiring lock_sock(sk).

iso_sock_clear_timer() reads iso_pi(sk)->conn twice without the socket lock held:

if (!iso_pi(sk)->conn)
    return;
cancel_delayed_work(&iso_pi(sk)->conn->timeout_work);

Concurrently, iso_conn_del() executes under lock_sock(sk) and calls iso_chan_del(), which sets iso_pi(sk)->conn to NULL and may result in the final reference to the connection being dropped:

CPU0                         CPU1
----                         ----
iso_sock_clear_timer()
  if (conn != NULL) ...      lock_sock(sk)
                               iso_chan_del()
                               iso_pi(sk)->conn = NULL
  cancel_delayed_work(conn)  /* NULL deref or UAF */

iso_pi(sk)->conn is not stable across the unlock window, causing a NULL pointer dereference or use-after-free.

Serialize iso_sock_clear_timer() with the socket lock by moving it inside lock_sock()/release_sock(), matching the pattern used in iso_conn_del() and all other call sites.

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/35f68f36d9883d56dec21cf85f7556d4657fc393
• https://git.kernel.org/stable/c/4b5f8e608749b7e8fa386c6e4301cf9272595859
• https://git.kernel.org/stable/c/51cb9dcfdf9a1bccf312ab2ae4b62db629f7dcd5
• https://git.kernel.org/stable/c/996c2104d0726a8fe584f85b3d6327197374a348
• https://git.kernel.org/stable/c/bc08c15746f25f41dd0508b25780d1e84acbb2ef
• https://git.kernel.org/stable/c/d9cbf7144ec589a3f0cc91f74a1a1af2d2b14afa