3.2.97-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Eric Biggers ebiggers@google.com
commit 13923d0865ca96312197962522e88bc0aedccd74 upstream.
A key of type "encrypted" references a "master key" which is used to encrypt and decrypt the encrypted key's payload. However, when we accessed the master key's payload, we failed to handle the case where the master key has been revoked, which sets the payload pointer to NULL. Note that 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.
This was an issue for master keys of type "user" only. Master keys can also be of type "trusted", but those cannot be revoked.
Fixes: 7e70cb497850 ("keys: add new key-type encrypted") Reviewed-by: James Morris james.l.morris@oracle.com Cc: Mimi Zohar zohar@linux.vnet.ibm.com Cc: David Safford safford@us.ibm.com Signed-off-by: Eric Biggers ebiggers@google.com Signed-off-by: David Howells dhowells@redhat.com [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- security/keys/encrypted-keys/encrypted.c | 7 +++++++ 1 file changed, 7 insertions(+)
--- a/security/keys/encrypted-keys/encrypted.c +++ b/security/keys/encrypted-keys/encrypted.c @@ -315,6 +315,13 @@ static struct key *request_user_key(cons
down_read(&ukey->sem); upayload = rcu_dereference(ukey->payload.data); + if (!upayload) { + /* key was revoked before we acquired its semaphore */ + up_read(&ukey->sem); + key_put(ukey); + ukey = ERR_PTR(-EKEYREVOKED); + goto error; + } *master_key = upayload->data; *master_keylen = upayload->datalen; error: