From: John Sheu sheu@google.com
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
--- drivers/base/dma-buf.c | 21 +++++++++++++++------ 1 files changed, 15 insertions(+), 6 deletions(-)
diff --git a/drivers/base/dma-buf.c b/drivers/base/dma-buf.c index 09e6878..06c6225 100644 --- a/drivers/base/dma-buf.c +++ b/drivers/base/dma-buf.c @@ -536,6 +536,9 @@ 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;
@@ -549,15 +552,21 @@ 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); - + get_file(dmabuf->file); + oldfile = vma->vm_file; vma->vm_file = dmabuf->file; - get_file(vma->vm_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);