ion: fix crash when alloc len is -1

If userspace passes a length between -4095 and -1 to allocate it
will pass the len != 0 check, but when len is page aligned it will
be 0.  Check len after page aligning.

Drop the warning as well, userspace shouldn't be able to trigger
a warning in the kernel.

Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c
index cf9fc78..2e7be70 100644 (file)
--- a/drivers/staging/android/ion/ion.c
+++ b/drivers/staging/android/ion/ion.c
@@ -485,11 +485,11 @@ struct ion_handle *ion_alloc(struct ion_client *client, size_t len,
         * request of the caller allocate from it.  Repeat until allocate has
         * succeeded or all heaps have been tried
         */
-       if (WARN_ON(!len))
-               return ERR_PTR(-EINVAL);
-
        len = PAGE_ALIGN(len);
 
+       if (!len)
+               return ERR_PTR(-EINVAL);
+
        down_read(&dev->lock);
        plist_for_each_entry(heap, &dev->heaps, node) {
                /* if the caller didn't specify this heap id */