On 10/9/21 08:35, Yan, Zheng wrote:
+CC Christoph
From: "Yan, Zheng" <yanzheng03@xxxxxxxxxxxx>
Device's minor is a 20-bits number, max value is 0xfffff.
Fixes: b1a811633f ("block: nbd: add sanity check for first_minor").
Signed-off-by: "Yan, Zheng" <yanzheng03@xxxxxxxxxxxx>
---
drivers/block/nbd.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 1183f7872b71..53cd038c96e9 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -1753,7 +1753,7 @@ static struct nbd_device *nbd_dev_add(int index, unsigned int refs)
* byte in __device_add_disk().
*/
disk->first_minor = index << part_shift;
- if (disk->first_minor > 0xff) {
+ if (disk->first_minor > MINORMASK) {
err = -EINVAL;
goto out_free_idr;
}
I've looked into what confused me with 0xff and I found that uapi's
kdev_t.h has following MINOR definition:
#define MINOR(dev) ((dev) & 0xff)
But kernel's kdev_t.h is really allows 20 bit minor number :)
Also, can you, please, fix up comment above this check, since it
contains info about max minor 0xff and it can confuse readers.
With regards,
Pavel Skripkin
