This is a note to let you know that I've just added the patch titled
nbd: fix possible overflow for 'first_minor' in nbd_dev_add()
to the 5.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
nbd-fix-possible-overflow-for-first_minor-in-nbd_dev.patch
and it can be found in the queue-5.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit a152c55ec1f97316360b1b532d709a2236057ba2
Author: Yu Kuai <yukuai3@xxxxxxxxxx>
Date: Tue Nov 2 09:52:35 2021 +0800
nbd: fix possible overflow for 'first_minor' in nbd_dev_add()
[ Upstream commit 940c264984fd1457918393c49674f6b39ee16506 ]
If 'part_shift' is not zero, then 'index << part_shift' might
overflow to a value that is not greater than '0xfffff', then sysfs
might complains about duplicate creation.
Fixes: b0d9111a2d53 ("nbd: use an idr to keep track of nbd devices")
Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
Reviewed-by: Josef Bacik <josef@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20211102015237.2309763-3-yebin10@xxxxxxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index bdc6d656e785c..f72ff515ee51b 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -1777,11 +1777,11 @@ static int nbd_dev_add(int index)
disk->major = NBD_MAJOR;
/* Too big first_minor can cause duplicate creation of
- * sysfs files/links, since MKDEV() expect that the max bits of
- * first_minor is 20.
+ * sysfs files/links, since index << part_shift might overflow, or
+ * MKDEV() expect that the max bits of first_minor is 20.
*/
disk->first_minor = index << part_shift;
- if (disk->first_minor > MINORMASK) {
+ if (disk->first_minor < index || disk->first_minor > MINORMASK) {
err = -EINVAL;
goto out_free_idr;
}
