From dcb04cc794835964c1efeea24b392e5e35e88ab8 Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Thu, 22 Feb 2018 14:38:33 +0000 Subject: X.509: fix BUG_ON() when hash algorithm is unsupported commit 437499eea4291ae9621e8763a41df027c110a1ef upstream. 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 Cc: Paolo Valente Cc: # v4.7+ Signed-off-by: Eric Biggers Signed-off-by: David Howells Signed-off-by: Greg Kroah-Hartman --- crypto/asymmetric_keys/public_key.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'crypto') diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c index 3cd6e12cfc46..d1af69d2ff85 100644 --- a/crypto/asymmetric_keys/public_key.c +++ b/crypto/asymmetric_keys/public_key.c @@ -93,9 +93,11 @@ 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 -- cgit v1.2.3