PM / devfreq: Fix kernel oops on governor module load

commit 7544fd7f384591038646d3cd9efb311ab4509e24 upstream.

A bit unexpectedly (but still documented), request_module may
return a positive value, in case of a modprobe error.
This is currently causing issues in the devfreq framework.

When a request_module exits with a positive value, we currently
return that via ERR_PTR. However, because the value is positive,
it's not a ERR_VALUE proper, and is therefore treated as a
valid struct devfreq_governor pointer, leading to a kernel oops.

Fix this by returning -EINVAL if request_module returns a positive
value.

Fixes: b53b0128052ff ("PM / devfreq: Fix static checker warning in try_then_request_governor")
Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Cc: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index e2ab46b..d350253 100644 (file)
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -257,7 +257,7 @@ static struct devfreq_governor *try_then_request_governor(const char *name)
                /* Restore previous state before return */
                mutex_lock(&devfreq_list_lock);
                if (err)
-                       return ERR_PTR(err);
+                       return (err < 0) ? ERR_PTR(err) : ERR_PTR(-EINVAL);
 
                governor = find_devfreq_governor(name);
        }