On Wed, Jul 02, 2025 at 08:29:45AM +0000, Xinyu Zheng wrote:

From: Dongli Zhang <redacted>

[ Upstream commit f591cf9fce724e5075cc67488c43c6e39e8cbe27 ]

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.

CVE-2025-38074

This is not needed.

Cc: stable@vger.kernel.org#5.10.x

What about 5.15.y and 6.1.y?  We can't take a patch just for 5.10 as
that would cause regressions, right?

Please provide all relevant backports and I will be glad to queue them
up then.  I'll drop this from my queue for now, thanks.

greg k-h