IB/core: disallow registering 0-sized memory region

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@opteya.com
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>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c
index 055ebeb..dccb9aa 100644 (file)
--- a/drivers/infiniband/core/umem.c
+++ b/drivers/infiniband/core/umem.c
@@ -94,6 +94,9 @@ 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.