[PATCH] block: add sanity check for uid in syscall of ioprio_get()

[Chengguang Xu <cgxu519@xxxxxxx>]

It better to validate uid info which is from userspace.

Signed-off-by: Chengguang Xu <cgxu519@xxxxxxx>
---
 block/ioprio.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/block/ioprio.c b/block/ioprio.c
index f9821080c92c..b59397662da6 100644
--- a/block/ioprio.c
+++ b/block/ioprio.c
@@ -218,6 +218,8 @@ SYSCALL_DEFINE2(ioprio_get, int, which, int, who)
 			break;
 		case IOPRIO_WHO_USER:
 			uid = make_kuid(current_user_ns(), who);
+			if (!uid_valid(uid))
+				break;
 			if (!who)
 				user = current_user();
 			else
-- 
2.17.2