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Fix word32 truncation and add true regression test for PKCS12 OOB read
1 parent 4cb016f commit 863db50

2 files changed

Lines changed: 124 additions & 4 deletions

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‎tests/api/test_pkcs12.c‎

Lines changed: 123 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -31,6 +31,7 @@
3131
#include <wolfssl/wolfcrypt/pkcs12.h>
3232
#include <wolfssl/wolfcrypt/pwdbased.h>
3333
#include <wolfssl/wolfcrypt/types.h>
34+
#include <wolfssl/wolfcrypt/aes.h>
3435
#include <tests/api/api.h>
3536
#include <tests/api/test_pkcs12.h>
3637

@@ -305,6 +306,7 @@ int test_wc_PKCS12_encrypted_content_bounds(void)
305306
byte* outKey = NULL;
306307
byte* outCert = NULL;
307308
WC_DerCertList* outCaList = NULL;
309+
int exportRet = 0;
308310
word32 pkcs12DerSz = 0;
309311
word32 outKeySz = 0;
310312
word32 outCertSz = 0;
@@ -314,8 +316,10 @@ int test_wc_PKCS12_encrypted_content_bounds(void)
314316
sizeof(pkcs12Passwd) - 1, NULL, inKey, inKeySz, inCert, inCertSz,
315317
&inCa, -1, -1, 2048, 2048, 0, NULL));
316318

317-
/* Serialize to DER */
318-
ExpectIntGE((pkcs12DerSz = wc_i2d_PKCS12(pkcs12Export, &pkcs12Der, NULL)), 0);
319+
/* Serialize to DER - use int intermediate to avoid word32 truncation
320+
* of negative error codes from wc_i2d_PKCS12(). */
321+
ExpectIntGE((exportRet = wc_i2d_PKCS12(pkcs12Export, &pkcs12Der, NULL)), 0);
322+
pkcs12DerSz = (word32)exportRet;
319323

320324
/* Parse it back - this exercises the fixed bounds checking code path */
321325
ExpectNotNull(pkcs12Import = wc_PKCS12_new_ex(NULL));
@@ -331,6 +335,9 @@ int test_wc_PKCS12_encrypted_content_bounds(void)
331335
ExpectIntEQ(outCertSz, inCertSz);
332336
ExpectNotNull(outCaList);
333337
ExpectIntEQ(outCaList->bufferSz, inCa.bufferSz);
338+
ExpectIntEQ(XMEMCMP(outKey, inKey, inKeySz), 0);
339+
ExpectIntEQ(XMEMCMP(outCert, inCert, inCertSz), 0);
340+
ExpectIntEQ(XMEMCMP(outCaList->buffer, inCa.buffer, inCa.bufferSz), 0);
334341

335342
/* Clean up */
336343
XFREE(outKey, NULL, DYNAMIC_TYPE_PUBLIC_KEY);
@@ -340,6 +347,120 @@ int test_wc_PKCS12_encrypted_content_bounds(void)
340347
XFREE(pkcs12Der, NULL, DYNAMIC_TYPE_PKCS);
341348
wc_PKCS12_free(pkcs12Export);
342349

350+
#endif
351+
352+
/* Part 2: True regression test - craft a malformed PKCS#12 whose decrypted
353+
* SafeBags SEQUENCE claims a length that exceeds the decrypted content
354+
* bounds (contentSz) but fits within the stale ContentInfo bounds
355+
* (ci->dataSz). Before the fix, the parser used ci->dataSz, allowing a
356+
* heap OOB read; with the fix it uses contentSz and rejects the blob. */
357+
#if !defined(NO_ASN) && !defined(NO_PWDBASED) && defined(HAVE_PKCS12) && \
358+
defined(WOLFSSL_AES_256) && defined(HAVE_AES_CBC) && \
359+
defined(HAVE_AES_DECRYPT) && !defined(NO_SHA256) && !defined(NO_HMAC) && \
360+
defined(WOLFSSL_ASN_TEMPLATE) && !defined(HAVE_FIPS)
361+
{
362+
static const char regPassword[] = "test";
363+
static const byte regSalt[8] = {1, 2, 3, 4, 5, 6, 7, 8};
364+
static const byte regIv[16] = {0};
365+
366+
/* Malformed SafeBags plaintext (one AES block = 16 bytes).
367+
* The outer SEQUENCE claims length 100 - this exceeds the decrypted
368+
* content size (16) but fits inside the stale ci->dataSz (127) that
369+
* the unfixed code used as the parsing bound. */
370+
static const byte regPlaintext[16] = {
371+
0x30, 0x64, /* SEQUENCE, length 100 */
372+
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
373+
0x00, 0x00, 0x00, 0x00, 0x00, 0x00
374+
};
375+
376+
/* Complete PKCS#12 DER (170 bytes).
377+
* Structure: PFX { version 3, authSafe { DATA { AuthenticatedSafe {
378+
* EncryptedData { PBES2(AES-256-CBC, HMAC-SHA256, PBKDF2)
379+
* <ciphertext placeholder at offset 154> } } } } }
380+
* No MacData - macIter=0 skips MAC verification. */
381+
byte regDer[170] = {
382+
0x30, 0x81, 0xA7, /* PFX SEQ (167) */
383+
0x02, 0x01, 0x03, /* version 3 */
384+
0x30, 0x81, 0xA1, /* authSafe ContentInfo (161) */
385+
0x06, 0x09, 0x2A, 0x86, 0x48, 0x86,
386+
0xF7, 0x0D, 0x01, 0x07, 0x01, /* OID data */
387+
0xA0, 0x81, 0x93, /* [0] CONS. (147) */
388+
0x04, 0x81, 0x90, /* OCTET STRING (144) */
389+
0x30, 0x81, 0x8D, /* AuthenticatedSafe SEQ (141) */
390+
0x30, 0x81, 0x8A, /* ContentInfo SEQ (138) */
391+
0x06, 0x09, 0x2A, 0x86, 0x48, 0x86,
392+
0xF7, 0x0D, 0x01, 0x07, 0x06, /* OID encryptedData */
393+
0xA0, 0x7D, /* [0] CONS. (125) */
394+
0x30, 0x7B, /* EncryptedData SEQ (123) */
395+
0x02, 0x01, 0x00, /* version 0 */
396+
0x30, 0x76, /* EncryptedContentInfo SEQ (118) */
397+
0x06, 0x09, 0x2A, 0x86, 0x48, 0x86,
398+
0xF7, 0x0D, 0x01, 0x07, 0x01, /* OID data */
399+
/* --- EncryptContent payload (107 bytes) --- */
400+
0x30, 0x57, /* AlgorithmIdentifier SEQ (87) */
401+
0x06, 0x09, 0x2A, 0x86, 0x48, 0x86,
402+
0xF7, 0x0D, 0x01, 0x05, 0x0D, /* OID pbes2 */
403+
0x30, 0x4A, /* PBES2-params SEQ (74) */
404+
0x30, 0x29, /* keyDerivFunc SEQ (41) */
405+
0x06, 0x09, 0x2A, 0x86, 0x48, 0x86,
406+
0xF7, 0x0D, 0x01, 0x05, 0x0C, /* OID pbkdf2 */
407+
0x30, 0x1C, /* PBKDF2-params SEQ (28) */
408+
0x04, 0x08,
409+
0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, /* salt */
410+
0x02, 0x02, 0x08, 0x00, /* iterations 2048 */
411+
0x30, 0x0C, /* PRF SEQ (12) */
412+
0x06, 0x08, 0x2A, 0x86, 0x48, 0x86,
413+
0xF7, 0x0D, 0x02, 0x09, /* OID hmac-sha256 */
414+
0x05, 0x00, /* NULL */
415+
0x30, 0x1D, /* encryptionScheme SEQ (29) */
416+
0x06, 0x09, 0x60, 0x86, 0x48, 0x01,
417+
0x65, 0x03, 0x04, 0x01, 0x2A, /* OID aes256-cbc */
418+
0x04, 0x10, /* IV OCT (16) */
419+
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
420+
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
421+
0x80, 0x10, /* [0] IMPLICIT CT (16) */
422+
/* 16 bytes ciphertext - filled at runtime */
423+
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
424+
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
425+
};
426+
427+
byte regKey[32];
428+
byte regCiphertext[16];
429+
Aes regAes;
430+
WC_PKCS12* regP12 = NULL;
431+
byte* regPkey = NULL;
432+
byte* regCert = NULL;
433+
word32 regPkeySz = 0;
434+
word32 regCertSz = 0;
435+
436+
/* Derive AES-256 key with the same PBKDF2 that DecryptContent uses */
437+
ExpectIntEQ(wc_PBKDF2(regKey, (const byte*)regPassword,
438+
(int)XSTRLEN(regPassword), regSalt, (int)sizeof(regSalt),
439+
2048, 32, WC_SHA256), 0);
440+
441+
/* Encrypt the malformed plaintext */
442+
ExpectIntEQ(wc_AesInit(&regAes, NULL, INVALID_DEVID), 0);
443+
ExpectIntEQ(wc_AesSetKey(&regAes, regKey, 32, regIv,
444+
AES_ENCRYPTION), 0);
445+
ExpectIntEQ(wc_AesCbcEncrypt(&regAes, regCiphertext, regPlaintext,
446+
sizeof(regPlaintext)), 0);
447+
wc_AesFree(&regAes);
448+
449+
/* Patch ciphertext into the DER template at offset 154 */
450+
XMEMCPY(regDer + 154, regCiphertext, sizeof(regCiphertext));
451+
452+
/* Parse the crafted PKCS#12 - d2i should succeed (outer structure
453+
* is valid), but wc_PKCS12_parse must fail because GetSequence
454+
* rejects SEQUENCE length 100 against contentSz 16. */
455+
ExpectNotNull(regP12 = wc_PKCS12_new_ex(NULL));
456+
ExpectIntGE(wc_d2i_PKCS12(regDer, (word32)sizeof(regDer), regP12), 0);
457+
ExpectIntLT(wc_PKCS12_parse(regP12, regPassword, &regPkey, &regPkeySz,
458+
&regCert, &regCertSz, NULL), 0);
459+
460+
XFREE(regPkey, NULL, DYNAMIC_TYPE_PUBLIC_KEY);
461+
XFREE(regCert, NULL, DYNAMIC_TYPE_PKCS);
462+
wc_PKCS12_free(regP12);
463+
}
343464
#endif
344465
return EXPECT_RESULT();
345466
}
@@ -747,4 +868,3 @@ int test_wc_PKCS12_PBKDF_ex_sha512_256(void)
747868
#endif
748869
return EXPECT_RESULT();
749870
}
750-

‎wolfcrypt/src/pkcs12.c‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1335,7 +1335,7 @@ int wc_PKCS12_parse_ex(WC_PKCS12* pkcs12, const char* psw,
13351335
byte* buf = NULL;
13361336
word32 i, oid;
13371337
word32 algId;
1338-
word32 contentSz;
1338+
word32 contentSz = 0;
13391339
int ret, pswSz;
13401340
#ifdef ASN_BER_TO_DER
13411341
int curIdx;

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