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Commit f73d1e6c authored by Eugene Teo's avatar Eugene Teo Committed by Rusty Russell
Browse files

lguest: make sure cpu is initialized before accessing it 



If req is LHREQ_INITIALIZE, and the guest has been initialized before
(unlikely), it will attempt to access cpu->tsk even though cpu is not yet
initialized.

Signed-off-by: default avatarEugene Teo <eugeneteo@kernel.sg>
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
parent cdeeeae0

drivers/lguest/lguest_user.c

+8 −7
Original line number Diff line number Diff line
@@ -241,15 +241,16 @@ static ssize_t write(struct file *file, const char __user *in, 
		cpu = &lg->cpus[cpu_id];

		if (!cpu)

			return -EINVAL;

	}



	/* Once the Guest is dead, all you can do is read() why it died. */

	if (lg && lg->dead)

		/* Once the Guest is dead, you can only read() why it died. */

		if (lg->dead)

			return -ENOENT;



	/* If you're not the task which owns the Guest, you can only break */

	if (lg && current != cpu->tsk && req != LHREQ_BREAK)

		/* If you're not the task which owns the Guest, all you can do

		 * is break the Launcher out of running the Guest. */

		if (current != cpu->tsk && req != LHREQ_BREAK)

			return -EPERM;

	}



	switch (req) {

	case LHREQ_INITIALIZE: