staging: alarm-dev: information leak in alarm_compat_ioctl()

If we pass an invalid clock type then "ts" is never set.  We need to
check for errors earlier, otherwise we end up passing uninitialized
stack data to userspace.

Reported-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 3 insertions, 1 deletions

diff --git a/drivers/staging/android/alarm-dev.c b/drivers/staging/android/alarm-dev.c
index c8600d96b9df..6dc27dac679d 100644
--- a/drivers/staging/android/alarm-dev.c
+++ b/drivers/staging/android/alarm-dev.c
@@ -297,6 +297,8 @@ static long alarm_compat_ioctl(struct file *file, unsigned int cmd,
         }
 
         rv = alarm_do_ioctl(file, cmd, &ts);
+        if (rv)
+                return rv;
 
         switch (ANDROID_ALARM_BASE_CMD(cmd)) {
         case ANDROID_ALARM_GET_TIME(0): /* NOTE: we modified cmd above */
@@ -305,7 +307,7 @@ static long alarm_compat_ioctl(struct file *file, unsigned int cmd,
                 break;
         }
 
-        return rv;
+        return 0;
 }
 #endif