block: check minor range in device_add_disk()

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@uniontech.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/b1b19379-23ee-5379-0eb5-94bf5f79f1b4@i-love.sakura.ne.jp
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/genhd.c b/block/genhd.c
index 603db5d..626c840 100644 (file)
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -431,6 +431,8 @@ 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;