[PATCH] KEYS: Use acquire when reading state in keyring search

[Gui-Dong Han]

The negative-key race fix added release/acquire ordering for key use.

Publish payload before state; read state before payload.

keyring_search_iterator() still uses READ_ONCE() before match callbacks.
An asymmetric match callback calls asymmetric_key_ids(), which reads
key->payload.data[asym_key_ids].

Use key_read_state() there to complete that ordering.

Fixes: 363b02dab09b ("KEYS: Fix race between updating and finding a negative key")
Signed-off-by: Gui-Dong Han <hanguidong02@xxxxxxxxx>
---
Found by auditing READ_ONCE() used for synchronization.
A similar fix can be found in 8df672bfe3ec.
---
 security/keys/keyring.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/security/keys/keyring.c b/security/keys/keyring.c
index b39038f7dd31..243fb1636f10 100644
--- a/security/keys/keyring.c
+++ b/security/keys/keyring.c
@@ -576,7 +576,7 @@ static int keyring_search_iterator(const void *object, void *iterator_data)
 	struct keyring_search_context *ctx = iterator_data;
 	const struct key *key = keyring_ptr_to_key(object);
 	unsigned long kflags = READ_ONCE(key->flags);
-	short state = READ_ONCE(key->state);
+	short state = key_read_state(key);
 
 	kenter("{%d}", key->serial);
 
-- 
2.34.1