Add NULL checks where ContentInfo data can be NULL

PKCS12 structures contain PKCS7 ContentInfo fields. These fields are
optional and can be NULL even if the "type" is a valid value. OpenSSL
was not properly accounting for this and a NULL dereference can occur
causing a crash.

CVE-2024-0727

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Hugo Landau <hlandau@openssl.org>
Reviewed-by: Neil Horman <nhorman@openssl.org>
(Merged from #23362)

Author: mattcaswell

crypto/pkcs12/p12_add.c

@@ -78,6 +78,12 @@ STACK_OF(PKCS12_SAFEBAG) *PKCS12_unpack_p7data(PKCS7 *p7)
         ERR_raise(ERR_LIB_PKCS12, PKCS12_R_CONTENT_TYPE_NOT_DATA);
         return NULL;
     }
+
+    if (p7->d.data == NULL) {
+        ERR_raise(ERR_LIB_PKCS12, PKCS12_R_DECODE_ERROR);
+        return NULL;
+    }
+
     return ASN1_item_unpack(p7->d.data, ASN1_ITEM_rptr(PKCS12_SAFEBAGS));
 }
 
@@ -150,6 +156,12 @@ STACK_OF(PKCS12_SAFEBAG) *PKCS12_unpack_p7encdata(PKCS7 *p7, const char *pass,
 {
     if (!PKCS7_type_is_encrypted(p7))
         return NULL;
+
+    if (p7->d.encrypted == NULL) {
+        ERR_raise(ERR_LIB_PKCS12, PKCS12_R_DECODE_ERROR);
+        return NULL;
+    }
+
     return PKCS12_item_decrypt_d2i_ex(p7->d.encrypted->enc_data->algorithm,
                                    ASN1_ITEM_rptr(PKCS12_SAFEBAGS),
                                    pass, passlen,
@@ -188,6 +200,12 @@ STACK_OF(PKCS7) *PKCS12_unpack_authsafes(const PKCS12 *p12)
         ERR_raise(ERR_LIB_PKCS12, PKCS12_R_CONTENT_TYPE_NOT_DATA);
         return NULL;
     }
+
+    if (p12->authsafes->d.data == NULL) {
+        ERR_raise(ERR_LIB_PKCS12, PKCS12_R_DECODE_ERROR);
+        return NULL;
+    }
+
     p7s = ASN1_item_unpack(p12->authsafes->d.data,
                            ASN1_ITEM_rptr(PKCS12_AUTHSAFES));
     if (p7s != NULL) {

crypto/pkcs12/p12_mutl.c

@@ -98,6 +98,11 @@ static int pkcs12_gen_mac(PKCS12 *p12, const char *pass, int passlen,
         return 0;
     }
 
+    if (p12->authsafes->d.data == NULL) {
+        ERR_raise(ERR_LIB_PKCS12, PKCS12_R_DECODE_ERROR);
+        return 0;
+    }
+
     salt = p12->mac->salt->data;
     saltlen = p12->mac->salt->length;
     if (p12->mac->iter == NULL)

crypto/pkcs12/p12_npas.c

@@ -77,8 +77,9 @@ static int newpass_p12(PKCS12 *p12, const char *oldpass, const char *newpass)
             bags = PKCS12_unpack_p7data(p7);
         } else if (bagnid == NID_pkcs7_encrypted) {
             bags = PKCS12_unpack_p7encdata(p7, oldpass, -1);
-            if (!alg_get(p7->d.encrypted->enc_data->algorithm,
-                         &pbe_nid, &pbe_iter, &pbe_saltlen))
+            if (p7->d.encrypted == NULL
+                    || !alg_get(p7->d.encrypted->enc_data->algorithm,
+                                &pbe_nid, &pbe_iter, &pbe_saltlen))
                 goto err;
         } else {
             continue;

crypto/pkcs7/pk7_mime.c

@@ -33,10 +33,13 @@ int SMIME_write_PKCS7(BIO *bio, PKCS7 *p7, BIO *data, int flags)
     int ctype_nid = OBJ_obj2nid(p7->type);
     const PKCS7_CTX *ctx = ossl_pkcs7_get0_ctx(p7);
 
-    if (ctype_nid == NID_pkcs7_signed)
+    if (ctype_nid == NID_pkcs7_signed) {
+        if (p7->d.sign == NULL)
+            return 0;
         mdalgs = p7->d.sign->md_algs;
-    else
+    } else {
         mdalgs = NULL;
+    }
 
     flags ^= SMIME_OLDMIME;