CVE-2025-38074 — vhost-scsi: protect vq->log_used with vq->mutex

Affected: Linux

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

vhost-scsi: protect vq->log_used with vq->mutex

The vhost-scsi completion path may access vq->log_base when vq->log_used is already set to false.

vhost-thread QEMU-thread

vhost_scsi_complete_cmd_work() -> vhost_add_used() -> vhost_add_used_n() if (unlikely(vq->log_used)) QEMU disables vq->log_used via VHOST_SET_VRING_ADDR. mutex_lock(&vq->mutex); vq->log_used = false now! mutex_unlock(&vq->mutex);

QEMU gfree(vq->log_base) log_used() -> log_write(vq->log_base)

Assuming the VMM is QEMU. The vq->log_base is from QEMU userpace and can be reclaimed via gfree(). As a result, this causes invalid memory writes to QEMU userspace.

The control queue path has the same issue.

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CVE-2025-38074 — vhost-scsi: protect vq->log_used with vq->mutex