PKCS#7: Fix NULL dereference with missing EncryptedContent.

CVE-2015-1790

Reviewed-by: Rich Salz <rsalz@openssl.org>

diff --git a/crypto/pkcs7/pk7_doit.c b/crypto/pkcs7/pk7_doit.c
index 31a1b983f1d9d175752af9c8ad7a52308c1a22d9..c8d7db01bd730c3f6887ec2ff610075789016864 100644 (file)
--- a/crypto/pkcs7/pk7_doit.c
+++ b/crypto/pkcs7/pk7_doit.c
@@ -445,6 +445,12 @@ BIO *PKCS7_dataDecode(PKCS7 *p7, EVP_PKEY *pkey, BIO *in_bio, X509 *pcert)
 
     switch (i) {
     case NID_pkcs7_signed:
+        /*
+         * p7->d.sign->contents is a PKCS7 structure consisting of a contentType
+         * field and optional content.
+         * data_body is NULL if that structure has no (=detached) content
+         * or if the contentType is wrong (i.e., not "data").
+         */
         data_body = PKCS7_get_octet_string(p7->d.sign->contents);
         if (!PKCS7_is_detached(p7) && data_body == NULL) {
             PKCS7err(PKCS7_F_PKCS7_DATADECODE,
@@ -456,6 +462,7 @@ BIO *PKCS7_dataDecode(PKCS7 *p7, EVP_PKEY *pkey, BIO *in_bio, X509 *pcert)
     case NID_pkcs7_signedAndEnveloped:
         rsk = p7->d.signed_and_enveloped->recipientinfo;
         md_sk = p7->d.signed_and_enveloped->md_algs;
+        /* data_body is NULL if the optional EncryptedContent is missing. */
         data_body = p7->d.signed_and_enveloped->enc_data->enc_data;
         enc_alg = p7->d.signed_and_enveloped->enc_data->algorithm;
         evp_cipher = EVP_get_cipherbyobj(enc_alg->algorithm);
@@ -468,6 +475,7 @@ BIO *PKCS7_dataDecode(PKCS7 *p7, EVP_PKEY *pkey, BIO *in_bio, X509 *pcert)
     case NID_pkcs7_enveloped:
         rsk = p7->d.enveloped->recipientinfo;
         enc_alg = p7->d.enveloped->enc_data->algorithm;
+        /* data_body is NULL if the optional EncryptedContent is missing. */
         data_body = p7->d.enveloped->enc_data->enc_data;
         evp_cipher = EVP_get_cipherbyobj(enc_alg->algorithm);
         if (evp_cipher == NULL) {
@@ -481,6 +489,12 @@ BIO *PKCS7_dataDecode(PKCS7 *p7, EVP_PKEY *pkey, BIO *in_bio, X509 *pcert)
         goto err;
     }
 
+    /* Detached content must be supplied via in_bio instead. */
+    if (data_body == NULL && in_bio == NULL) {
+        PKCS7err(PKCS7_F_PKCS7_DATADECODE, PKCS7_R_NO_CONTENT);
+        goto err;
+    }
+
     /* We will be checking the signature */
     if (md_sk != NULL) {
         for (i = 0; i < sk_X509_ALGOR_num(md_sk); i++) {
@@ -623,7 +637,7 @@ BIO *PKCS7_dataDecode(PKCS7 *p7, EVP_PKEY *pkey, BIO *in_bio, X509 *pcert)
         etmp = NULL;
     }
 #if 1
-    if (PKCS7_is_detached(p7) || (in_bio != NULL)) {
+    if (in_bio != NULL) {
         bio = in_bio;
     } else {
 # if 0