Use kmalloc_flex() when allocating a new struct user_key_payload in
user_preparse() to replace the open-coded size arithmetic and to keep
the size type-safe.

Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
---
 security/keys/user_defined.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/security/keys/user_defined.c b/security/keys/user_defined.c
index 686d56e4cc85..6f88b507f927 100644
--- a/security/keys/user_defined.c
+++ b/security/keys/user_defined.c
@@ -64,7 +64,7 @@ int user_preparse(struct key_preparsed_payload *prep)
 	if (datalen == 0 || datalen > 32767 || !prep->data)
 		return -EINVAL;
 
-	upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL);
+	upayload = kmalloc_flex(*upayload, data, datalen);
 	if (!upayload)
 		return -ENOMEM;