[3.16.y-ckt stable] Patch "IB/core: disallow registering 0-sized memory region" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    IB/core: disallow registering 0-sized memory region

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt11.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

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>From 4aa6e6a09d74dcb5ccbbab068fcb2600553dcb6a Mon Sep 17 00:00:00 2001
From: Yann Droneaud <ydroneaud at opteya.com>
Date: Mon, 13 Apr 2015 14:56:22 +0200
Subject: 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 at mellanox.com>
Cc: Jack Morgenstein <jackm at mellanox.com>
Cc: Or Gerlitz <ogerlitz at mellanox.com>
Signed-off-by: Yann Droneaud <ydroneaud at opteya.com>
Signed-off-by: Doug Ledford <dledford at redhat.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/infiniband/core/umem.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c
index 0b2584dbeba0..9cc7af4bca94 100644
--- 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.