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lguest: make sure cpu is initialized before accessing it

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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: Eugene Teo <eugeneteo@kernel.sg>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Eugene Teo 2008-02-09 23:53:17 +08:00 committed by Rusty Russell
parent cdeeeae056
commit f73d1e6ca6
1 changed files with 9 additions and 8 deletions
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17
drivers/lguest/lguest_user.c
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@ -241,16 +241,17 @@ 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, you can only read() why it died. */
if (lg->dead)
return -ENOENT;
/* 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;
}
/* Once the Guest is dead, all you can do is read() why it died. */
if (lg && 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)
return -EPERM;
switch (req) {
case LHREQ_INITIALIZE:
return initialize(file, input);