ext4 crypto: add missing locking for keyring_key access

Cc: stable@kernel.org
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

1 files changed, 4 insertions, 0 deletions

diff --git a/fs/ext4/crypto_key.c b/fs/ext4/crypto_key.c
index c5882b36e558..9a16d1e75a49 100644
--- a/fs/ext4/crypto_key.c
+++ b/fs/ext4/crypto_key.c
@@ -213,9 +213,11 @@ retry:
                 res = -ENOKEY;
                 goto out;
         }
+        down_read(&keyring_key->sem);
         ukp = user_key_payload(keyring_key);
         if (ukp->datalen != sizeof(struct ext4_encryption_key)) {
                 res = -EINVAL;
+                up_read(&keyring_key->sem);
                 goto out;
         }
         master_key = (struct ext4_encryption_key *)ukp->data;
@@ -226,10 +228,12 @@ retry:
                             "ext4: key size incorrect: %d\n",
                             master_key->size);
                 res = -ENOKEY;
+                up_read(&keyring_key->sem);
                 goto out;
         }
         res = ext4_derive_key_aes(ctx.nonce, master_key->raw,
                                   raw_key);
+        up_read(&keyring_key->sem);
         if (res)
                 goto out;
 got_key: