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-rw-r--r--fs/crypto/keyring.c15
1 files changed, 12 insertions, 3 deletions
diff --git a/fs/crypto/keyring.c b/fs/crypto/keyring.c
index 7f8ac61a20d6..71d56f8e2870 100644
--- a/fs/crypto/keyring.c
+++ b/fs/crypto/keyring.c
@@ -213,7 +213,11 @@ static int allocate_filesystem_keyring(struct super_block *sb)
if (IS_ERR(keyring))
return PTR_ERR(keyring);
- /* Pairs with READ_ONCE() in fscrypt_find_master_key() */
+ /*
+ * Pairs with the smp_load_acquire() in fscrypt_find_master_key().
+ * I.e., here we publish ->s_master_keys with a RELEASE barrier so that
+ * concurrent tasks can ACQUIRE it.
+ */
smp_store_release(&sb->s_master_keys, keyring);
return 0;
}
@@ -234,8 +238,13 @@ struct key *fscrypt_find_master_key(struct super_block *sb,
struct key *keyring;
char description[FSCRYPT_MK_DESCRIPTION_SIZE];
- /* pairs with smp_store_release() in allocate_filesystem_keyring() */
- keyring = READ_ONCE(sb->s_master_keys);
+ /*
+ * Pairs with the smp_store_release() in allocate_filesystem_keyring().
+ * I.e., another task can publish ->s_master_keys concurrently,
+ * executing a RELEASE barrier. We need to use smp_load_acquire() here
+ * to safely ACQUIRE the memory the other task published.
+ */
+ keyring = smp_load_acquire(&sb->s_master_keys);
if (keyring == NULL)
return ERR_PTR(-ENOKEY); /* No keyring yet, so no keys yet. */