| From | Kamal Mostafa <> | Subject | [PATCH 089/133] virtio: console: fix race in port_fops_open() and port unplug | Date | Fri, 16 Aug 2013 15:33:51 -0700 |
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3.8.13.7 -stable review patch. If anyone has any objections, please let me know.
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From: Amit Shah <amit.shah@redhat.com>
commit 671bdea2b9f210566610603ecbb6584c8a201c8c upstream.
Between open() being called and processed, the port can be unplugged. Check if this happened, and bail out.
A simple test script to reproduce this is:
while true; do for i in $(seq 1 100); do echo $i > /dev/vport0p3; done; done;
This opens and closes the port a lot of times; unplugging the port while this is happening triggers the bug.
Signed-off-by: Amit Shah <amit.shah@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- drivers/char/virtio_console.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c index ff015e7..4e848c8 100644 --- a/drivers/char/virtio_console.c +++ b/drivers/char/virtio_console.c @@ -1047,6 +1047,10 @@ static int port_fops_open(struct inode *inode, struct file *filp) /* We get the port with a kref here */ port = find_port_by_devt(cdev->dev); + if (!port) { + /* Port was unplugged before we could proceed */ + return -ENXIO; + } filp->private_data = port; /* -- 1.8.1.2
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