[PATCH 3.17 123/319] media: vmalloc_sg: off by one in error handling

[Greg Kroah-Hartman]

3.17-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Dan Carpenter <dan.carpenter@xxxxxxxxxx>

commit 23d3090f8b44ab42162e99e8584445bc25b8922f upstream.

The "i--" needs to happen at the start of the loop or it will try to
release something bogus (probably it will crash) and it won't release
the first ->vaddr_page[].

Fixes: 7b4eeed174b7 ('[media] vmalloc_sg: make sure all pages in vmalloc area are really DMA-ready')

Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/media/v4l2-core/videobuf-dma-sg.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/drivers/media/v4l2-core/videobuf-dma-sg.c
+++ b/drivers/media/v4l2-core/videobuf-dma-sg.c
@@ -253,9 +253,11 @@ int videobuf_dma_init_kernel(struct vide
 	return 0;
 out_free_pages:
 	while (i > 0) {
-		void *addr = page_address(dma->vaddr_pages[i]);
-		dma_free_coherent(dma->dev, PAGE_SIZE, addr, dma->dma_addr[i]);
+		void *addr;
+
 		i--;
+		addr = page_address(dma->vaddr_pages[i]);
+		dma_free_coherent(dma->dev, PAGE_SIZE, addr, dma->dma_addr[i]);
 	}
 	kfree(dma->dma_addr);
 	dma->dma_addr = NULL;


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