[PATCH 5.15 581/846] block: check minor range in device_add_disk()

[Greg Kroah-Hartman]

From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>

[ 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@xxxxxxxxxxxxx>
Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Link: https://lore.kernel.org/r/b1b19379-23ee-5379-0eb5-94bf5f79f1b4@xxxxxxxxxxxxxxxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 block/genhd.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/block/genhd.c b/block/genhd.c
index 22f899615801c..de789d1a1e3d2 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -420,6 +420,8 @@ int 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