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authorEugene Teo <eugeneteo@kernel.sg>2008-02-09 23:53:17 +0800
committerRusty Russell <rusty@rustcorp.com.au>2008-03-11 09:35:56 +1100
commitf73d1e6ca6985b43a1871467463cba632fbc624d (patch)
tree84b01e87f41bf960c58b6934142da31f6d1638eb /drivers/lguest
parentcdeeeae056a429e729ae9e914fa8142ee45bee93 (diff)
downloadlwn-f73d1e6ca6985b43a1871467463cba632fbc624d.tar.gz
lwn-f73d1e6ca6985b43a1871467463cba632fbc624d.zip
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: Eugene Teo <eugeneteo@kernel.sg> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'drivers/lguest')
-rw-r--r--drivers/lguest/lguest_user.c15
1 files changed, 8 insertions, 7 deletions
diff --git a/drivers/lguest/lguest_user.c b/drivers/lguest/lguest_user.c
index 85d42d3d01a9..2221485b0773 100644
--- a/drivers/lguest/lguest_user.c
+++ b/drivers/lguest/lguest_user.c
@@ -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)
- return -ENOENT;
+ /* 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)
- return -EPERM;
+ /* 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: