virtio_console: fix hot-unplug races in TX paths

When a port is hot-unplugged, unplug_port() nullifies port->portdev.
However, concurrent TX paths (__send_to_port, put_chars) could read a
stale pointer or encounter a NULL pointer dereference.

Add READ_ONCE(port->portdev) and NULL checks in the TX paths. In
__send_to_port(), move the out_vq assignment inside the outvq_lock and
check portdev under the lock. Correspondingly, update unplug_port() to
NULL out port->portdev while holding the outvq_lock to serialize with
__send_to_port().

In put_chars(), return count instead of 0 on unplug to prevent the hvc
layer from spinning in an infinite retry loop.

Signed-off-by: Sungho Bae <baver.bae@lge.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Message-ID: <20260603183757.21587-3-baver.bae@gmail.com>

0 files changed, 0 insertions, 0 deletions