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From:   Ben Hutchings <ben@decadent.org.uk>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
CC:     akpm@linux-foundation.org,
        "Mohamed Ghannam" <simo.ghannam@gmail.com>,
        "David S. Miller" <davem@davemloft.net>
Date:   Sun, 11 Feb 2018 04:20:06 +0000
Message-ID: <lsq.1518322806.701824887@decadent.org.uk>
Subject: [PATCH 3.2 67/79] RDS: Heap OOB write in rds_message_alloc_sgs()
In-Reply-To: <lsq.1518322802.943358572@decadent.org.uk>
Sender: linux-kernel-owner@vger.kernel.org
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3.2.99-rc1 review patch.  If anyone has any objections, please let me know.

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

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

commit c095508770aebf1b9218e77026e48345d719b17c upstream.

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>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 net/rds/rdma.c | 3 +++
 1 file changed, 3 insertions(+)

--- a/net/rds/rdma.c
+++ b/net/rds/rdma.c
@@ -516,6 +516,9 @@ int rds_rdma_extra_size(struct rds_rdma_
 
 	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],