goldfish: locking bugs in goldfish_pipe_read_write()

We recently messed up the error handling here.  We can return with the
pipe->lock held or sometimes we unlock twice by mistake.

Fixes: 2f3be88237a3 ('goldfish_pipe: Pin pages to memory while copying and other cleanups')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/platform/goldfish/goldfish_pipe.c b/drivers/platform/goldfish/goldfish_pipe.c
index e3fab9a1d9f7783a8e1f27346a3568407f9b593e..839df4aace764631ab9b0599ab08460e73f465cb 100644 (file)
--- a/drivers/platform/goldfish/goldfish_pipe.c
+++ b/drivers/platform/goldfish/goldfish_pipe.c
@@ -313,7 +313,7 @@ static ssize_t goldfish_pipe_read_write(struct file *filp, char __user *buffer,
                                     !is_write, 0, &page, NULL);
                up_read(&current->mm->mmap_sem);
                if (ret < 0)
-                       return ret;
+                       break;
 
                if (dev->version) {
                        /* Device version 1 or newer (qemu-android) expects the
@@ -400,22 +400,16 @@ static ssize_t goldfish_pipe_read_write(struct file *filp, char __user *buffer,
                while (test_bit(wakeBit, &pipe->flags)) {
                        if (wait_event_interruptible(
                                        pipe->wake_queue,
-                                       !test_bit(wakeBit, &pipe->flags))) {
-                               ret = -ERESTARTSYS;
-                               break;
-                       }
-
-                       if (test_bit(BIT_CLOSED_ON_HOST, &pipe->flags)) {
-                               ret = -EIO;
-                               break;
-                       }
+                                       !test_bit(wakeBit, &pipe->flags)))
+                               return -ERESTARTSYS;
+
+                       if (test_bit(BIT_CLOSED_ON_HOST, &pipe->flags))
+                               return -EIO;
                }
 
                /* Try to re-acquire the lock */
-               if (mutex_lock_interruptible(&pipe->lock)) {
-                       ret = -ERESTARTSYS;
-                       break;
-               }
+               if (mutex_lock_interruptible(&pipe->lock))
+                       return -ERESTARTSYS;
        }
        mutex_unlock(&pipe->lock);