linux-kernel - [PATCH] block: add check of 'minors' and 'first_minor' in device_add

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Date: Tue, 19 Dec 2023 15:59:42 +0800
From: linan666@...weicloud.com
To: axboe@...nel.dk,
	penguin-kernel@...ove.sakura.ne.jp
Cc: linux-block@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linan666@...weicloud.com,
	yukuai3@...wei.com,
	yi.zhang@...wei.com,
	houtao1@...wei.com,
	yangerkun@...wei.com
Subject: [PATCH] block: add check of 'minors' and 'first_minor' in device_add_disk()

From: Li Nan <linan122@...wei.com>

'first_minor' represents the starting minor number of disks, and
'minors' represents the number of partitions in the device. Neither
of them can be greater than MINORMASK + 1.

Commit e338924bd05d ("block: check minor range in device_add_disk()")
only added the check of 'first_minor + minors'. However, their sum might
be less than MINORMASK but their values are wrong. Complete the checks now.

Fixes: e338924bd05d ("block: check minor range in device_add_disk()")
Signed-off-by: Li Nan <linan122@...wei.com>
---
 block/genhd.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/block/genhd.c b/block/genhd.c
index c9d06f72c587..551b5693ebd5 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -432,7 +432,9 @@ int __must_check device_add_disk(struct device *parent, struct gendisk *disk,
 				DISK_MAX_PARTS);
 			disk->minors = DISK_MAX_PARTS;
 		}
-		if (disk->first_minor + disk->minors > MINORMASK + 1)
+		if (disk->first_minor > MINORMASK ||
+		    disk->minors > MINORMASK + 1 ||
+		    disk->first_minor + disk->minors > MINORMASK + 1)
 			goto out_exit_elevator;
 	} else {
 		if (WARN_ON(disk->minors))
-- 
2.39.2