virtio_console: do not free control-out buffers on remove

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__send_control_msg() publishes &portdev->cpkt as the control-out
virtqueue cookie. remove_vqs() walks every virtqueue and passes leftover
cookies to free_buf(), which treats them as struct port_buffer and
reads sgpages.

If a control message is still on c_ovq when the device is unbound,
free_buf() reads past the ports_device object.

KASAN reported slab-out-of-bounds in free_buf():

	free_buf
	remove_vqs
	virtcons_remove
	unbind_store

The object was the ports_device allocated in virtcons_probe().

Drain c_ovq without freeing. The packet lives in portdev and is released
with it.

Fixes: a7a69ec0d8 ("virtio_console: free buffers after reset")
Signed-off-by: Jia Jia <physicalmtea@gmail.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Message-ID: <20260819021230.292696-1-physicalmtea@gmail.com>

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Jia Jia 2026-08-19 10:12:30 +08:00 • committed by Michael S. Tsirkin

parent 3f9a0fceb7

commit 894f98e739

1 changed files with 18 additions and 3 deletions

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drivers/char/virtio_console.c

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