1 files changed, 23 insertions, 7 deletions

diff --git a/source/helpers/pkcs7/pkcs7-openssl.c b/source/helpers/pkcs7/pkcs7-openssl.c
index 1468b7e1..58dbf65f 100644
--- a/source/helpers/pkcs7/pkcs7-openssl.c
+++ b/source/helpers/pkcs7/pkcs7-openssl.c
@@ -633,10 +633,12 @@ static int signer_create_digest(pdf_pkcs7_signer *signer, fz_stream *in, unsigne
 	unsigned char *p7_ptr;
 	int p7_len;
 
-	bdata = BIO_new_stream(ctx, in);
-	if (bdata == NULL)
-		goto exit;
-
+	if (in != NULL)
+	{
+		bdata = BIO_new_stream(ctx, in);
+		if (bdata == NULL)
+			goto exit;
+	}
 
 	p7 = PKCS7_new();
 	if (p7 == NULL)
@@ -657,7 +659,7 @@ static int signer_create_digest(pdf_pkcs7_signer *signer, fz_stream *in, unsigne
 	if (bp7in == NULL)
 		goto exit;
 
-	while(1)
+	while(bdata) /* bdata knowingly not changed in the loop */
 	{
 		char buf[4096];
 		int n = BIO_read(bdata, buf, sizeof(buf));
@@ -677,10 +679,12 @@ static int signer_create_digest(pdf_pkcs7_signer *signer, fz_stream *in, unsigne
 		goto exit;
 
 	p7_len = BIO_get_mem_data(bp7, &p7_ptr);
-	if (p7_len > *digest_len)
+	if (digest && p7_len > *digest_len)
 		goto exit;
 
-	memcpy(digest, p7_ptr, p7_len);
+	if (digest)
+		memcpy(digest, p7_ptr, p7_len);
+
 	*digest_len = p7_len;
 	res = 1;
 
@@ -692,6 +696,17 @@ exit:
 	return res;
 }
 
+static int max_digest_size(pdf_pkcs7_signer *signer)
+{
+	/* Perform a test digest generation to find the required size. Size
+	 * is assumed independent of data being hashed */
+	int digest_len = 0;
+
+	signer_create_digest(signer, NULL, NULL, &digest_len);
+
+	return digest_len;
+}
+
 pdf_pkcs7_signer *pkcs7_openssl_read_pfx(fz_context *ctx, const char *pfile, const char *pw)
 {
 	BIO *pfxbio = NULL;
@@ -710,6 +725,7 @@ pdf_pkcs7_signer *pkcs7_openssl_read_pfx(fz_context *ctx, const char *pfile, con
 		signer->base.drop = drop_signer;
 		signer->base.designated_name = signer_designated_name;
 		signer->base.drop_designated_name = signer_drop_designated_name;
+		signer->base.max_digest_size = max_digest_size;
 		signer->base.create_digest = signer_create_digest;
 		signer->ctx = ctx;
 		signer->refs = 1;