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Subject[PATCH 7/9] videobuf2/videobuf2-dma-sg.c: Convert to use vm_insert_range_buggy
Convert to use vm_insert_range_buggy to map range of kernel memory
to user vma.

This driver has ignored vm_pgoff. We could later "fix" these drivers
to behave according to the normal vm_pgoff offsetting simply by
removing the _buggy suffix on the function name and if that causes
regressions, it gives us an easy way to revert.

There is an existing bug inside gem_mmap_obj(), where user passed
length is not checked against buf->num_pages. For any value of
length > buf->num_pages it will end up overrun buf->pages[i],
which could lead to a potential bug.

This has been addressed by passing buf->num_pages as input to
vm_insert_range_buggy() and inside this API error condition is
checked which will avoid overrun the page boundary.

Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
---
drivers/media/common/videobuf2/videobuf2-dma-sg.c | 22 ++++++----------------
1 file changed, 6 insertions(+), 16 deletions(-)

diff --git a/drivers/media/common/videobuf2/videobuf2-dma-sg.c b/drivers/media/common/videobuf2/videobuf2-dma-sg.c
index 015e737..ef046b4 100644
--- a/drivers/media/common/videobuf2/videobuf2-dma-sg.c
+++ b/drivers/media/common/videobuf2/videobuf2-dma-sg.c
@@ -328,28 +328,18 @@ static unsigned int vb2_dma_sg_num_users(void *buf_priv)
static int vb2_dma_sg_mmap(void *buf_priv, struct vm_area_struct *vma)
{
struct vb2_dma_sg_buf *buf = buf_priv;
- unsigned long uaddr = vma->vm_start;
- unsigned long usize = vma->vm_end - vma->vm_start;
- int i = 0;
+ int err;

if (!buf) {
printk(KERN_ERR "No memory to map\n");
return -EINVAL;
}

- do {
- int ret;
-
- ret = vm_insert_page(vma, uaddr, buf->pages[i++]);
- if (ret) {
- printk(KERN_ERR "Remapping memory, error: %d\n", ret);
- return ret;
- }
-
- uaddr += PAGE_SIZE;
- usize -= PAGE_SIZE;
- } while (usize > 0);
-
+ err = vm_insert_range_buggy(vma, buf->pages, buf->num_pages);
+ if (err) {
+ printk(KERN_ERR "Remapping memory, error: %d\n", err);
+ return err;
+ }

/*
* Use common vm_area operations to track buffer refcount.
--
1.9.1
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