CVE-2026-72306: vduse: Fix race in vduse_dev_msg_sync and vduse_dev_read_iter

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

vduse: Fix race in vdusedevmsgsync and vdusedevreaditer

There is one race case in vdusedevmsgsync and vdusedevreaditer:

vdusedevreaditer(): lock(msglock); dequeuemsg(sendlist); unlock(msglock); vdusedevmsgsync(): waittimeout() finish lock(msglock); check msg->complete is false listdel(msg); <- double listdel() crash!

To fix this case, we shall ensure vdusemsg is on sendlist or recvlist outside the msglock critical section.