CHROMIUM: dma-buf: restore args on failure of dma_buf_mmap

Callers to dma_buf_mmap expect to fput() the vma struct's vm_file
themselves on failure.  Not restoring the struct's data on failure
causes a double-decrement of the vm_file's refcount.

Signed-off-by: John Sheu <sheu@google.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>

1 files changed, 17 insertions, 6 deletions

diff --git a/drivers/base/dma-buf.c b/drivers/base/dma-buf.c
index 394523807a6d..2a7cb0df176b 100644
--- a/drivers/base/dma-buf.c
+++ b/drivers/base/dma-buf.c
@@ -447,6 +447,9 @@ EXPORT_SYMBOL_GPL(dma_buf_kunmap);
 int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,
                  unsigned long pgoff)
 {
+        struct file *oldfile;
+        int ret;
+
         if (WARN_ON(!dmabuf || !vma))
                 return -EINVAL;
 
@@ -460,14 +463,22 @@ int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,
                 return -EINVAL;
 
         /* readjust the vma */
-        if (vma->vm_file)
-                fput(vma->vm_file);
-
-        vma->vm_file = get_file(dmabuf->file);
-
+        get_file(dmabuf->file);
+        oldfile = vma->vm_file;
+        vma->vm_file = dmabuf->file;
         vma->vm_pgoff = pgoff;
 
-        return dmabuf->ops->mmap(dmabuf, vma);
+        ret = dmabuf->ops->mmap(dmabuf, vma);
+        if (ret) {
+                /* restore old parameters on failure */
+                vma->vm_file = oldfile;
+                fput(dmabuf->file);
+        } else {
+                if (oldfile)
+                        fput(oldfile);
+        }
+        return ret;
+
 }
 EXPORT_SYMBOL_GPL(dma_buf_mmap);