From f73d1e6ca6985b43a1871467463cba632fbc624d Mon Sep 17 00:00:00 2001 From: Eugene Teo 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 Signed-off-by: Rusty Russell --- drivers/lguest/lguest_user.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 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 @@ -241,16 +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);