[PATCH 3.2 043/164] IB/core: disallow registering 0-sized memory region

[Ben Hutchings]

3.2.70-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Yann Droneaud <ydroneaud@xxxxxxxxxx>

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/cover.1428929103.git.ydroneaud@xxxxxxxxxx
Cc: Shachar Raindel <raindel@xxxxxxxxxxxx>
Cc: Jack Morgenstein <jackm@xxxxxxxxxxxx>
Cc: Or Gerlitz <ogerlitz@xxxxxxxxxxxx>
Signed-off-by: Yann Droneaud <ydroneaud@xxxxxxxxxx>
Signed-off-by: Doug Ledford <dledford@xxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 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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