CVE-2026-90206

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

nvmet: fix max_qid race between configfs and controller allocation

The function nvmet_subsys_attr_qid_max_store() can race against nvmet_alloc_ctrl() when a subsystems max_qid limit is modified.

Suppose max_qid is currently 64. If nvmet_alloc_ctrl() executes: ctrl->sqs = kzalloc_objs(struct nvmet_sq *, subsys->max_qid + 1); and at this exact point, a userspace process changes max_qid to 128, nvmet_subsys_attr_qid_max_store() will set the new max_qid value. It attempts to delete active controllers to force a reconnect, but the new controller wont be deleted because it hasnt been added to the subsys->ctrls list yet.

nvmet_alloc_ctrl() then proceeds and adds the new controller to the subsys->ctrls list. Later, when nvmet_install_queue() is called, it will see max_qid set to 128, but the memory allocated for sqs is only sized for 64 entries. This results in a KASAN out-of-bounds warning and potential memory corruptions.

Fix this by protecting the queue allocations and list insertion in nvmet_alloc_ctrl() with down_read(&nvmet_config_sem). Because nvmet_subsys_attr_qid_max_store() acquires down_write(&nvmet_config_sem) to modify the attribute, this safely prevents the configfs writer from modifying max_qid during controller creation.

Copy the max_qid from the subsystem to the controllers structure during the allocation; ctrl->max_qid never changes as long as the controller remains in LIVE state, so this will prevent similar race conditions.

Affected Software

References

• https://git.kernel.org/stable/c/2c23fc91789dfd9db746edb3ae9b90d65fabd410
• https://git.kernel.org/stable/c/f1a8846e06388113dfdbb89dee005083fa9afdf9