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

Vulnerability Description

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.

References

• https://git.kernel.org/stable/c/80cf68489681c165ded460930e391b1eb37b5f6f
• https://git.kernel.org/stable/c/8312a1ccff1566f375191a89b9ba71b6eb48a8cd
• https://git.kernel.org/stable/c/59614c5acf6688f7af3c245d359082c0e9e53117
• https://git.kernel.org/stable/c/ca85c2d0db5f8309832be45858b960d933c2131c
• https://git.kernel.org/stable/c/bd8c9404e44adb9f6219c09b3409a61ab7ce3427
• https://git.kernel.org/stable/c/c0039e3afda29be469d29b3013d7f9bdee136834
• https://git.kernel.org/stable/c/f591cf9fce724e5075cc67488c43c6e39e8cbe27