CVE-2026-89486

/// Technical description

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

ipmi: Fix use-after-free of cmd_rcvr in _ipmi_destroy_user()

Commit 9e91f8a6c868 ("ipmi:msghandler: Remove srcu for the

ipmi_interfaces list") dropped the synchronize_rcu() between unlinking

the command receivers from intf->cmd_rcvrs and freeing them, updating

only the comment that explains why the barrier is needed.

The cmd_rcvrs list is still traversed under plain RCU: find_cmd_rcvr()

walks it inside rcu_read_lock(), and handle_ipmb_get_msg_cmd() borrows

rcvr->user from that lookup within the same read-side section. Without

the grace period, _ipmi_destroy_user() can kfree() a cmd_rcvr while a

reader still holds a pointer to it, causing a use-after-free.

The rework only made srcu unnecessary for the interfaces list; the

cmd_rcvrs list still relies on plain RCU. Restore the synchronize_rcu()

before freeing the receivers.

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References