From f73d1e6ca6985b43a1871467463cba632fbc624d Mon Sep 17 00:00:00 2001
From: Eugene Teo <eugeneteo@kernel.sg>
Date: Sat, 9 Feb 2008 23:53:17 +0800
Subject: [PATCH] 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>
---
drivers/lguest/lguest_user.c | 15 ++++++++-------
1 file 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:
--
GitLab