linux-kernel - [PATCH] nullb: Adjust device size calculation in null_alloc

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Message-ID: <20240917070729.15752-1-amishin@t-argos.ru>
Date: Tue, 17 Sep 2024 10:07:29 +0300
From: Aleksandr Mishin <amishin@...rgos.ru>
To: Shaohua Li <shli@...com>
CC: Aleksandr Mishin <amishin@...rgos.ru>, Jens Axboe <axboe@...nel.dk>,
	Damien Le Moal <dlemoal@...nel.org>, Hannes Reinecke <hare@...e.de>, Johannes
 Thumshirn <johannes.thumshirn@....com>, Chaitanya Kulkarni <kch@...dia.com>,
	Zhu Yanjun <yanjun.zhu@...ux.dev>, Chengming Zhou
	<zhouchengming@...edance.com>, John Garry <john.g.garry@...cle.com>, Yu Kuai
	<yukuai3@...wei.com>, Shin'ichiro Kawasaki <shinichiro.kawasaki@....com>,
	<linux-block@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<lvc-project@...uxtesting.org>
Subject: [PATCH] nullb: Adjust device size calculation in null_alloc_dev()

In null_alloc_dev() device size is a subject to overflow because 'g_gb'
(which is module parameter, may have any value and is not validated
anywhere) is not cast to a larger data type before performing arithmetic.

Cast 'g_gb' to unsigned long to prevent overflow.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 2984c8684f96 ("nullb: factor disk parameters")
Signed-off-by: Aleksandr Mishin <amishin@...rgos.ru>
---
 drivers/block/null_blk/main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
index 2f0431e42c49..5edbf9c0aceb 100644
--- a/drivers/block/null_blk/main.c
+++ b/drivers/block/null_blk/main.c
@@ -762,7 +762,7 @@ static struct nullb_device *null_alloc_dev(void)
 		return NULL;
 	}
 
-	dev->size = g_gb * 1024;
+	dev->size = (unsigned long)g_gb * 1024;
 	dev->completion_nsec = g_completion_nsec;
 	dev->submit_queues = g_submit_queues;
 	dev->prev_submit_queues = g_submit_queues;
-- 
2.30.2