This is a note to let you know that I've just added the patch titled fscrypt: fix dereference of NULL user_key_payload to the 4.13-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: fscrypt-fix-dereference-of-null-user_key_payload.patch and it can be found in the queue-4.13 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From d60b5b7854c3d135b869f74fb93eaf63cbb1991a Mon Sep 17 00:00:00 2001 From: Eric Biggers <ebiggers@xxxxxxxxxx> Date: Mon, 9 Oct 2017 12:46:18 -0700 Subject: fscrypt: fix dereference of NULL user_key_payload From: Eric Biggers <ebiggers@xxxxxxxxxx> commit d60b5b7854c3d135b869f74fb93eaf63cbb1991a upstream. 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: 88bd6ccdcdd6 ("ext4 crypto: add encryption key management facilities") Reviewed-by: James Morris <james.l.morris@xxxxxxxxxx> Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx> Signed-off-by: David Howells <dhowells@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/crypto/keyinfo.c | 5 +++++ 1 file changed, 5 insertions(+) --- a/fs/crypto/keyinfo.c +++ b/fs/crypto/keyinfo.c @@ -109,6 +109,11 @@ static int validate_user_key(struct fscr goto out; } ukp = user_key_payload_locked(keyring_key); + if (!ukp) { + /* key was revoked before we acquired its semaphore */ + res = -EKEYREVOKED; + goto out; + } if (ukp->datalen != sizeof(struct fscrypt_key)) { res = -EINVAL; goto out; Patches currently in stable-queue which might be from ebiggers@xxxxxxxxxx are queue-4.13/keys-fix-race-between-updating-and-finding-a-negative-key.patch queue-4.13/fs-cache-fix-dereference-of-null-user_key_payload.patch queue-4.13/lib-digsig-fix-dereference-of-null-user_key_payload.patch queue-4.13/ecryptfs-fix-dereference-of-null-user_key_payload.patch queue-4.13/fscrypt-fix-dereference-of-null-user_key_payload.patch queue-4.13/keys-encrypted-fix-dereference-of-null-user_key_payload.patch queue-4.13/keys-don-t-let-add_key-update-an-uninstantiated-key.patch