KEYS: user: Align the payload buffer

ebiggers · James Morris · commit cc1780fc42c7 · 2019-02-22T10:11:19.000-08:00
Align the payload of "user" and "logon" keys so that users of the keyrings service can access it as a struct that requires more than 2-byte alignment. fscrypt currently does this which results in the read of fscrypt_key::size being misaligned as it needs 4-byte alignment. Align to __alignof__(u64) rather than __alignof__(long) since in the future it's conceivable that people would use structs beginning with u64, which on some platforms would require more than 'long' alignment. Reported-by: Aaro Koskinen <aaro.koskinen@iki.fi> Fixes: 2aa349f ("[PATCH] Keys: Export user-defined keyring operations") Fixes: 88bd6cc ("ext4 crypto: add encryption key management facilities") Cc: stable@vger.kernel.org Signed-off-by: Eric Biggers <ebiggers@google.com> Tested-by: Aaro Koskinen <aaro.koskinen@iki.fi> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: James Morris <james.morris@microsoft.com>
diff --git a/include/keys/user-type.h b/include/keys/user-type.h
@@ -31,7 +31,7 @@
 struct user_key_payload {
 	struct rcu_head	rcu;		/* RCU destructor */
 	unsigned short	datalen;	/* length of this data */
-	char		data[0];	/* actual data */
+	char		data[0] __aligned(__alignof__(u64)); /* actual data */
 };
 
 extern struct key_type key_type_user;
