From c095508770aebf1b9218e77026e48345d719b17c Mon Sep 17 00:00:00 2001

From: Mohamed Ghannam <simo.ghannam@gmail.com>

Date: Tue, 2 Jan 2018 19:44:34 +0000

Subject: [PATCH] RDS: Heap OOB write in rds_message_alloc_sgs()

When args->nr_local is 0, nr_pages gets also 0 due some size

calculation via rds_rm_size(), which is later used to allocate

pages for DMA, this bug produces a heap Out-Of-Bound write access

to a specific memory region.

Signed-off-by: Mohamed Ghannam <simo.ghannam@gmail.com>

Signed-off-by: David S. Miller <davem@davemloft.net>

---

 net/rds/rdma.c | 3 +++

 1 file changed, 3 insertions(+)

diff --git a/net/rds/rdma.c b/net/rds/rdma.c

index bc2f1e0977d6..94729d9da437 100644

--- a/net/rds/rdma.c

+++ b/net/rds/rdma.c

@@ -525,6 +525,9 @@ int rds_rdma_extra_size(struct rds_rdma_args *args)

 	local_vec = (struct rds_iovec __user *)(unsigned long) args->local_vec_addr;

+	if (args->nr_local == 0)

+		return -EINVAL;

+

 	/* figure out the number of pages in the vector */

 	for (i = 0; i < args->nr_local; i++) {

 		if (copy_from_user(&vec, &local_vec[i],

-- 

2.15.1