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

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

From: Yann Droneaud <[email protected]>

commit 8abaae62f3fdead8f4ce0ab46b4ab93dee39bab2 upstream.

If ib_umem_get() is called with a size equal to 0 and an
non-page aligned address, one page will be pinned and a
0-sized umem will be returned to the caller.

This should not be allowed: it's not expected for a memory
region to have a size equal to 0.

This patch adds a check to explicitly refuse to register
a 0-sized region.

Link: http://mid.gmane.org/[email protected]
Cc: Shachar Raindel <[email protected]>
Cc: Jack Morgenstein <[email protected]>
Cc: Or Gerlitz <[email protected]>
Signed-off-by: Yann Droneaud <[email protected]>
Signed-off-by: Doug Ledford <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

---
 drivers/infiniband/core/umem.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/drivers/infiniband/core/umem.c
+++ b/drivers/infiniband/core/umem.c
@@ -94,6 +94,9 @@ struct ib_umem *ib_umem_get(struct ib_uc
        if (dmasync)
                dma_set_attr(DMA_ATTR_WRITE_BARRIER, &attrs);
 
+       if (!size)
+               return ERR_PTR(-EINVAL);
+
        /*
         * If the combination of the addr and size requested for this memory
         * region causes an integer overflow, return error.


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