From: Eric Biggers ebiggers@google.com
The X.509 parser mishandles the case where the certificate's signature's hash algorithm is not available in the crypto API. In this case, x509_get_sig_params() doesn't allocate the cert->sig->digest buffer; this part seems to be intentional. However, public_key_verify_signature() is still called via x509_check_for_self_signed(), which triggers the 'BUG_ON(!sig->digest)'.
Fix this by making public_key_verify_signature() return -ENOPKG if the hash buffer has not been allocated.
Reproducer when all the CONFIG_CRYPTO_SHA512* options are disabled:
openssl req -new -sha512 -x509 -batch -nodes -outform der \ | keyctl padd asymmetric desc @s
Fixes: 6c2dc5ae4ab7 ("X.509: Extract signature digest and make self-signed cert checks earlier") Reported-by: Paolo Valente paolo.valente@linaro.org Cc: Paolo Valente paolo.valente@linaro.org Cc: stable@vger.kernel.org # v4.7+ Signed-off-by: Eric Biggers ebiggers@google.com Signed-off-by: David Howells dhowells@redhat.com ---
crypto/asymmetric_keys/public_key.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c index de996586762a..e929fe1e4106 100644 --- a/crypto/asymmetric_keys/public_key.c +++ b/crypto/asymmetric_keys/public_key.c @@ -79,9 +79,11 @@ int public_key_verify_signature(const struct public_key *pkey,
BUG_ON(!pkey); BUG_ON(!sig); - BUG_ON(!sig->digest); BUG_ON(!sig->s);
+ if (!sig->digest) + return -ENOPKG; + alg_name = sig->pkey_algo; if (strcmp(sig->pkey_algo, "rsa") == 0) { /* The data wangled by the RSA algorithm is typically padded