On Mon, Oct 09, 2017 at 12:46:18PM -0700, Eric Biggers wrote:

From: Eric Biggers <redacted>

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 <redacted>
Cc: <redacted>    [v4.1+]
Signed-off-by: Eric Biggers <redacted>

Applied, thanks.

					- Ted
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