linux-kernel - [PATCH AUTOSEL 5.16 170/217] block: check minor range in device_add

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Date:   Mon, 17 Jan 2022 21:18:53 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
        wangyangbo <wangyangbo@...ontech.com>,
        Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
        Christoph Hellwig <hch@....de>, Jens Axboe <axboe@...nel.dk>,
        Sasha Levin <sashal@...nel.org>, linux-block@...r.kernel.org
Subject: [PATCH AUTOSEL 5.16 170/217] block: check minor range in device_add_disk()

From: Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>

[ Upstream commit e338924bd05d6e71574bc13e310c89e10e49a8a5 ]

ioctl(fd, LOOP_CTL_ADD, 1048576) causes

  sysfs: cannot create duplicate filename '/dev/block/7:0'

message because such request is treated as if ioctl(fd, LOOP_CTL_ADD, 0)
due to MINORMASK == 1048575. Verify that all minor numbers for that device
fit in the minor range.

Reported-by: wangyangbo <wangyangbo@...ontech.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
Reviewed-by: Christoph Hellwig <hch@....de>
Link: https://lore.kernel.org/r/b1b19379-23ee-5379-0eb5-94bf5f79f1b4@i-love.sakura.ne.jp
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 block/genhd.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/block/genhd.c b/block/genhd.c
index 30362aeacac4b..b0847f7a90c50 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -425,6 +425,8 @@ 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)
+			return -EINVAL;
 	} else {
 		if (WARN_ON(disk->minors))
 			return -EINVAL;
-- 
2.34.1