Backport of:

From 09df4395b5071217b76dc7d3d2e630eb8c5a79c2 Mon Sep 17 00:00:00 2001
From: Matt Caswell <matt@openssl.org>
Date: Fri, 19 Jan 2024 11:28:58 +0000
Subject: [PATCH] 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 https://github.com/openssl/openssl/pull/23362)

(cherry picked from commit d135eeab8a5dbf72b3da5240bab9ddb7678dbd2c)
---
 crypto/pkcs12/p12_add.c  | 18 ++++++++++++++++++
 crypto/pkcs12/p12_mutl.c |  5 +++++
 crypto/pkcs12/p12_npas.c |  5 +++--
 crypto/pkcs7/pk7_mime.c  |  7 +++++--
 4 files changed, 31 insertions(+), 4 deletions(-)

--- a/crypto/pkcs12/p12_add.c
+++ b/crypto/pkcs12/p12_add.c
@@ -76,6 +76,13 @@ STACK_OF(PKCS12_SAFEBAG) *PKCS12_unpack_
                   PKCS12_R_CONTENT_TYPE_NOT_DATA);
         return NULL;
     }
+
+    if (p7->d.data == NULL) {
+        PKCS12err(PKCS12_F_PKCS12_UNPACK_P7DATA,
+                  PKCS12_R_DECODE_ERROR);
+        return NULL;
+    }
+
     return ASN1_item_unpack(p7->d.data, ASN1_ITEM_rptr(PKCS12_SAFEBAGS));
 }
 
@@ -132,6 +139,12 @@ STACK_OF(PKCS12_SAFEBAG) *PKCS12_unpack_
 {
     if (!PKCS7_type_is_encrypted(p7))
         return NULL;
+
+    if (p7->d.encrypted == NULL) {
+        PKCS12err(PKCS12_F_PKCS12_UNPACK_P7DATA, PKCS12_R_DECODE_ERROR);
+        return NULL;
+    }
+
     return PKCS12_item_decrypt_d2i(p7->d.encrypted->enc_data->algorithm,
                                    ASN1_ITEM_rptr(PKCS12_SAFEBAGS),
                                    pass, passlen,
@@ -159,6 +172,13 @@ STACK_OF(PKCS7) *PKCS12_unpack_authsafes
                   PKCS12_R_CONTENT_TYPE_NOT_DATA);
         return NULL;
     }
+
+    if (p12->authsafes->d.data == NULL) {
+        PKCS12err(PKCS12_F_PKCS12_UNPACK_AUTHSAFES,
+                  PKCS12_R_DECODE_ERROR);
+        return NULL;
+    }
+
     return ASN1_item_unpack(p12->authsafes->d.data,
                             ASN1_ITEM_rptr(PKCS12_AUTHSAFES));
 }
--- a/crypto/pkcs12/p12_mutl.c
+++ b/crypto/pkcs12/p12_mutl.c
@@ -93,6 +93,11 @@ static int pkcs12_gen_mac(PKCS12 *p12, c
         return 0;
     }
 
+    if (p12->authsafes->d.data == NULL) {
+        PKCS12err(PKCS12_F_PKCS12_GEN_MAC, PKCS12_R_DECODE_ERROR);
+        return 0;
+    }
+
     salt = p12->mac->salt->data;
     saltlen = p12->mac->salt->length;
     if (!p12->mac->iter)
--- a/crypto/pkcs12/p12_npas.c
+++ b/crypto/pkcs12/p12_npas.c
@@ -78,8 +78,9 @@ static int newpass_p12(PKCS12 *p12, cons
             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;
--- a/crypto/pkcs7/pk7_mime.c
+++ b/crypto/pkcs7/pk7_mime.c
@@ -30,10 +30,13 @@ int SMIME_write_PKCS7(BIO *bio, PKCS7 *p
 {
     STACK_OF(X509_ALGOR) *mdalgs;
     int ctype_nid = OBJ_obj2nid(p7->type);
-    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;