> From: Kimberly Brown <kimbrownkd@xxxxxxxxx> > Sent: Monday, January 21, 2019 6:08 PM > Subject: [PATCH] Drivers: hv: vmbus: Add mutex lock to channel show functions > > The channel level "_show" functions are vulnerable to race conditions. > Add a mutex lock and unlock around the call to the channel level "_show" > functions in vmbus_chan_attr_show(). > > This problem was discussed here: > https://lkml.org/lkml/2018/10/18/830 > > --- a/drivers/hv/vmbus_drv.c > +++ b/drivers/hv/vmbus_drv.c > @@ -1414,6 +1414,7 @@ static ssize_t vmbus_chan_attr_show(struct kobject > *kobj, > = container_of(attr, struct vmbus_chan_attribute, attr); > const struct vmbus_channel *chan > = container_of(kobj, struct vmbus_channel, kobj); > + ssize_t ret; > > if (!attribute->show) > return -EIO; > @@ -1421,7 +1422,10 @@ static ssize_t vmbus_chan_attr_show(struct > kobject *kobj, > if (chan->state != CHANNEL_OPENED_STATE) > return -EINVAL; > > - return attribute->show(chan, buf); > + mutex_lock(&vmbus_connection.channel_mutex); > + ret = attribute->show(chan, buf); > + mutex_unlock(&vmbus_connection.channel_mutex); > + return ret; > } It looks this patch is already able to fix the original issue: 6712cc9c2211 ("vmbus: don't return values for uninitalized channels"), as chan->state can't be CHANNEL_OPENED_STATE when channel->ringbuffer_page is not set up yet, or has been freed. Thanks, -- Dexuan _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
