From c60e246f56738036a4962b0aa40ff7ffbad6ec5f Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Thu, 22 Feb 2018 14:38:33 +0000 Subject: [PATCH] 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(-) diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c index 4955eb66e361..8525fe474abd 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 -- 2.17.1