Commit 0227da01 authored by Christian König's avatar Christian König
Browse files

mm: mmap: fix fput in error path v2 



Patch "495c10cc CHROMIUM: dma-buf: restore args..."
adds a workaround for a bug in mmap_region.

As the comment states ->mmap() callback can change
vma->vm_file and so we might call fput() on the wrong file.

Revert the workaround and proper fix this in mmap_region.

v2: drop the extra if in dma_buf_mmap as well

Signed-off-by: default avatarChristian König <christian.koenig@amd.com>
Reviewed-by: default avatarJason Gunthorpe <jgg@nvidia.com>
Link: https://patchwork.freedesktop.org/patch/394772/
parent ea86f3de

drivers/dma-buf/dma-buf.c

+3 −17
Original line number Diff line number Diff line
@@ -1166,9 +1166,6 @@ EXPORT_SYMBOL_GPL(dma_buf_end_cpu_access); 
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;
@@ -1186,22 +1183,11 @@ int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma, 
		return -EINVAL;



	/* readjust the vma */

	get_file(dmabuf->file);

	oldfile = vma->vm_file;

	vma->vm_file = dmabuf->file;

	fput(vma->vm_file);

	vma->vm_file = get_file(dmabuf->file);

	vma->vm_pgoff = pgoff;



	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;



	return dmabuf->ops->mmap(dmabuf, vma);

}

EXPORT_SYMBOL_GPL(dma_buf_mmap);

mm/mmap.c

+1 −1
Original line number Diff line number Diff line
@@ -1899,8 +1899,8 @@ unsigned long mmap_region(struct file *file, unsigned long addr, 
	return addr;



unmap_and_free_vma:

	fput(vma->vm_file);

	vma->vm_file = NULL;

	fput(file);



	/* Undo any partial mapping done by a device driver. */

	unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);