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authorEric Biggers <ebiggers@google.com>2017-10-09 12:46:18 -0700
committerDavid Howells <dhowells@redhat.com>2017-10-12 17:16:40 +0100
commitd60b5b7854c3d135b869f74fb93eaf63cbb1991a (patch)
treebe7b147d0cb48d18f7069e053c4271dead139f94 /fs
parent192cabd6a296cbc57b3d8c05c4c89d87fc102506 (diff)
downloadlinux-d60b5b7854c3d135b869f74fb93eaf63cbb1991a.tar.bz2
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: 88bd6ccdcdd6 ("ext4 crypto: add encryption key management facilities") Reviewed-by: James Morris <james.l.morris@oracle.com> Cc: <stable@vger.kernel.org> [v4.1+] Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: David Howells <dhowells@redhat.com>
Diffstat (limited to 'fs')
-rw-r--r--fs/crypto/keyinfo.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/fs/crypto/keyinfo.c b/fs/crypto/keyinfo.c
index 018c588c7ac3..8e704d12a1cf 100644
--- a/fs/crypto/keyinfo.c
+++ b/fs/crypto/keyinfo.c
@@ -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+ /* key was revoked before we acquired its semaphore */
+ res = -EKEYREVOKED;
+ goto out;
+ }
if (ukp->datalen != sizeof(struct fscrypt_key)) {
res = -EINVAL;
goto out;