[PATCH -next v4 2/4] nbd: fix possible overflow for 'first_minor' in nbd_dev_add()
From: Yu Kuai <yukuai3@huawei.com>
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@huawei.com>
---
drivers/block/nbd.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 678ee2688f63..cc32b5bc0f49 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -1803,11 +1803,11 @@ static struct nbd_device *nbd_dev_add(int index, unsigned int refs)
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;
}
--
2.31.1
Reply to: