From: Eric Biggers Date: Mon, 9 Oct 2017 19:46:18 +0000 (-0700) Subject: fscrypt: fix dereference of NULL user_key_payload X-Git-Tag: v4.14-rc6~22^2~1^2~10 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=d60b5b7854c3d135b869f74fb93eaf63cbb1991a;p=platform%2Fkernel%2Flinux-exynos.git 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 Cc: [v4.1+] Signed-off-by: Eric Biggers Signed-off-by: David Howells --- diff --git a/fs/crypto/keyinfo.c b/fs/crypto/keyinfo.c index 018c588..8e704d1 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fscrypt_info *crypt_info, goto out; } ukp = user_key_payload_locked(keyring_key); + if (!ukp) { + /* key was revoked before we acquired its semaphore */ + res = -EKEYREVOKED; + goto out; + } if (ukp-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;