staging: ion: Fix possible null pointer dereference

The kbuild test robot reported:

drivers/staging/android/ion/ion_system_heap.c:122 alloc_largest_available() error: potential null dereference 'info'.  (kmalloc returns null)

Where the pointer returned from kmalloc goes unchecked for failure.

This patch checks the return for NULL, and reworks the logic, as
suggested by Colin, so we allocate the page_info structure first.

Acked-by: Colin Cross <ccross@android.com>
Cc: Android Kernel Team <kernel-team@android.com>
Reported-by: kbuild test robot <fengguang.wu@intel.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_system_heap.c b/drivers/staging/android/ion/ion_system_heap.c
index 144b22727505e6fefcb756cc4a5c72089baae1f0..7f0729130d6583d776734e9df7a89b234b150065 100644 (file)
--- a/drivers/staging/android/ion/ion_system_heap.c
+++ b/drivers/staging/android/ion/ion_system_heap.c
@@ -108,6 +108,10 @@ static struct page_info *alloc_largest_available(struct ion_system_heap *heap,
        struct page_info *info;
        int i;
 
+       info = kmalloc(sizeof(struct page_info), GFP_KERNEL);
+       if (!info)
+               return NULL;
+
        for (i = 0; i < num_orders; i++) {
                if (size < order_to_size(orders[i]))
                        continue;
@@ -118,11 +122,12 @@ static struct page_info *alloc_largest_available(struct ion_system_heap *heap,
                if (!page)
                        continue;
 
-               info = kmalloc(sizeof(struct page_info), GFP_KERNEL);
                info->page = page;
                info->order = orders[i];
                return info;
        }
+       kfree(info);
+
        return NULL;
 }