IB/core: disallow registering 0-sized memory region

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@opteya.com
Cc: <stable@vger.kernel.org>
Cc: Shachar Raindel <raindel@mellanox.com>
Cc: Jack Morgenstein <jackm@mellanox.com>
Cc: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Yann Droneaud <ydroneaud@opteya.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c
index 8c014b5dab4c..9ac4068d2088 100644
--- a/drivers/infiniband/core/umem.c
+++ b/drivers/infiniband/core/umem.c
@@ -99,6 +99,9 @@ struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr,
         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.