Commit d60b5b78 authored by Eric Biggers's avatar Eric Biggers Committed by David Howells
Browse files

fscrypt: fix dereference of NULL user_key_payload

When an fscrypt-encrypted file is opened, we request the file's master
key from the keyrings service as a logon key, then access its payload.
However, a revoked key has a NULL payload, and we failed to check for
this.  request_key() *does* skip revoked keys, but there is still a
window where the key can be revoked before we acquire its semaphore.

Fix it by checking for a NULL payload, treating it like a key which was
already revoked at the time it was requested.

Fixes: 88bd6ccd

 ("ext4 crypto: add encryption key management facilities")
Reviewed-by: default avatarJames Morris <>
Cc: <>    [v4.1+]
Signed-off-by: default avatarEric Biggers <>
Signed-off-by: default avatarDavid Howells <>
parent 192cabd6
......@@ -109,6 +109,11 @@ static int validate_user_key(struct fscrypt_info *crypt_info,
goto out;
ukp = user_key_payload_locked(keyring_key);
if (!ukp) {
/* key was revoked before we acquired its semaphore */
goto out;
if (ukp->datalen != sizeof(struct fscrypt_key)) {
res = -EINVAL;
goto out;
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