4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Eric Biggers <ebiggers@xxxxxxxxxx>
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 <paolo.valente@xxxxxxxxxx>
Cc: Paolo Valente <paolo.valente@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # v4.7+
Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
crypto/asymmetric_keys/public_key.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
--- a/crypto/asymmetric_keys/public_key.c
+++ b/crypto/asymmetric_keys/public_key.c
@@ -93,9 +93,11 @@ int public_key_verify_signature(const st
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