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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, John Pittman <jpittman@redhat.com>,
        Jens Axboe <axboe@kernel.dk>,
        "Sasha Levin (Microsoft)" <sashal@kernel.org>
Subject: [PATCH 5.0 078/122] null_blk: prevent crash from bad home_node value
Date:   Mon,  6 May 2019 16:32:16 +0200
Message-Id: <20190506143101.836774644@linuxfoundation.org>
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[ Upstream commit 7ff684a683d777c4956fce93e60accbab2bd7696 ]

At module load, if the selected home_node value is greater than
the available numa nodes, the system will crash in
__alloc_pages_nodemask() due to a bad paging request.  Prevent this
user error crash by detecting the bad value, logging an error, and
setting g_home_node back to the default of NUMA_NO_NODE.

Signed-off-by: John Pittman <jpittman@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin (Microsoft) <sashal@kernel.org>
---
 drivers/block/null_blk_main.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/block/null_blk_main.c b/drivers/block/null_blk_main.c
index 62c9654b9ce8..fd7a9be54595 100644
--- a/drivers/block/null_blk_main.c
+++ b/drivers/block/null_blk_main.c
@@ -1749,6 +1749,11 @@ static int __init null_init(void)
 		return -EINVAL;
 	}
 
+	if (g_home_node != NUMA_NO_NODE && g_home_node >= nr_online_nodes) {
+		pr_err("null_blk: invalid home_node value\n");
+		g_home_node = NUMA_NO_NODE;
+	}
+
 	if (g_queue_mode == NULL_Q_RQ) {
 		pr_err("null_blk: legacy IO path no longer available\n");
 		return -EINVAL;
-- 
2.20.1