From fb6165ff8f8ad1d7725f63e509eb7f7543df231e Mon Sep 17 00:00:00 2001 From: Henrique Nakashima Date: Tue, 10 Oct 2017 16:13:08 -0400 Subject: Fix dangling pointer to ID array in CPDF_SecurityHandler. This was caused by breaking the reference from CPDF_SecurityHandler to CPDF_Parser in https://pdfium-review.googlesource.com/c/pdfium/+/15290 The reference was replaced with a reference to the ID Array and a copy of the password. The issue is that when parsing PDFs with multiple trailers, the trailer containing the ID array may be replaced and destroyed in CPDF_Parser::TrailerData::SetMainTrailer() after being passed to CPDF_SecurityHandler, which would then have a dangling pointer to it. This CL changes the CPDF_SecurityHandler to hold a copy of the original file ID instead of all the ID Array. Bug: chromium:771479,chromium:772376 Change-Id: Id98100502093d890fc2fe6a3da139f910daf38f4 Reviewed-on: https://pdfium-review.googlesource.com/15910 Commit-Queue: Henrique Nakashima Reviewed-by: Tom Sepez Reviewed-by: Ryan Harrison --- core/fpdfapi/parser/cpdf_security_handler.cpp | 42 +++++++++++++-------------- core/fpdfapi/parser/cpdf_security_handler.h | 2 +- 2 files changed, 21 insertions(+), 23 deletions(-) (limited to 'core/fpdfapi') diff --git a/core/fpdfapi/parser/cpdf_security_handler.cpp b/core/fpdfapi/parser/cpdf_security_handler.cpp index 26202ec3ee..ca0891a729 100644 --- a/core/fpdfapi/parser/cpdf_security_handler.cpp +++ b/core/fpdfapi/parser/cpdf_security_handler.cpp @@ -31,7 +31,7 @@ void CalcEncryptKey(const CPDF_Dictionary* pEncrypt, uint8_t* key, int keylen, bool bIgnoreMeta, - const CPDF_Array* pIdArray) { + const ByteString& fileId) { int revision = pEncrypt->GetIntegerFor("R"); uint8_t passcode[32]; for (uint32_t i = 0; i < 32; i++) { @@ -46,10 +46,8 @@ void CalcEncryptKey(const CPDF_Dictionary* pEncrypt, CRYPT_MD5Update(&md5, (uint8_t*)okey.c_str(), okey.GetLength()); uint32_t perm = pEncrypt->GetIntegerFor("P"); CRYPT_MD5Update(&md5, (uint8_t*)&perm, 4); - if (pIdArray) { - ByteString id = pIdArray->GetStringAt(0); - CRYPT_MD5Update(&md5, (uint8_t*)id.c_str(), id.GetLength()); - } + if (!fileId.IsEmpty()) + CRYPT_MD5Update(&md5, (uint8_t*)fileId.c_str(), fileId.GetLength()); if (!bIgnoreMeta && revision >= 3 && !pEncrypt->GetIntegerFor("EncryptMetadata", 1)) { uint32_t tag = 0xFFFFFFFF; @@ -58,13 +56,11 @@ void CalcEncryptKey(const CPDF_Dictionary* pEncrypt, uint8_t digest[16]; CRYPT_MD5Finish(&md5, digest); uint32_t copy_len = keylen; - if (copy_len > sizeof(digest)) { + if (copy_len > sizeof(digest)) copy_len = sizeof(digest); - } if (revision >= 3) { - for (int i = 0; i < 50; i++) { + for (int i = 0; i < 50; i++) CRYPT_MD5Generate(digest, copy_len, digest); - } } memset(key, 0, keylen); memcpy(key, digest, copy_len); @@ -102,13 +98,11 @@ CPDF_SecurityHandler::~CPDF_SecurityHandler() {} bool CPDF_SecurityHandler::OnInit(const CPDF_Dictionary* pEncryptDict, const CPDF_Array* pIdArray, const ByteString& password) { - m_pIdArray = pIdArray; - if (!LoadDict(pEncryptDict)) { + m_FileId = pIdArray ? pIdArray->GetStringAt(0) : ""; + if (!LoadDict(pEncryptDict)) return false; - } - if (m_Cipher == FXCIPHER_NONE) { + if (m_Cipher == FXCIPHER_NONE) return true; - } if (!CheckSecurity(password)) return false; @@ -420,7 +414,7 @@ bool CPDF_SecurityHandler::CheckUserPassword(const ByteString& password, uint8_t* key, int32_t key_len) { CalcEncryptKey(m_pEncryptDict.Get(), password, key, key_len, - bIgnoreEncryptMeta, m_pIdArray.Get()); + bIgnoreEncryptMeta, m_FileId); ByteString ukey = m_pEncryptDict ? m_pEncryptDict->GetStringFor("U") : ByteString(); if (ukey.GetLength() < 16) { @@ -447,9 +441,8 @@ bool CPDF_SecurityHandler::CheckUserPassword(const ByteString& password, CRYPT_md5_context md5; CRYPT_MD5Start(&md5); CRYPT_MD5Update(&md5, defpasscode, 32); - if (m_pIdArray) { - ByteString id = m_pIdArray->GetStringAt(0); - CRYPT_MD5Update(&md5, (uint8_t*)id.c_str(), id.GetLength()); + if (!m_FileId.IsEmpty()) { + CRYPT_MD5Update(&md5, (uint8_t*)m_FileId.c_str(), m_FileId.GetLength()); } CRYPT_MD5Finish(&md5, ukeybuf); return memcmp(test, ukeybuf, 16) == 0; @@ -581,8 +574,14 @@ void CPDF_SecurityHandler::OnCreateInternal(CPDF_Dictionary* pEncryptDict, } pEncryptDict->SetNewFor("O", ByteString(passcode, 32), false); } + + ByteString fileId; + if (pIdArray) { + fileId = pIdArray->GetStringAt(0); + } + CalcEncryptKey(m_pEncryptDict.Get(), user_password, m_EncryptKey, key_len, - false, pIdArray); + false, fileId); if (m_Revision < 3) { uint8_t tempbuf[32]; memcpy(tempbuf, defpasscode, 32); @@ -592,9 +591,8 @@ void CPDF_SecurityHandler::OnCreateInternal(CPDF_Dictionary* pEncryptDict, CRYPT_md5_context md5; CRYPT_MD5Start(&md5); CRYPT_MD5Update(&md5, defpasscode, 32); - if (pIdArray) { - ByteString id = pIdArray->GetStringAt(0); - CRYPT_MD5Update(&md5, (uint8_t*)id.c_str(), id.GetLength()); + if (!fileId.IsEmpty()) { + CRYPT_MD5Update(&md5, (uint8_t*)fileId.c_str(), fileId.GetLength()); } uint8_t digest[32]; CRYPT_MD5Finish(&md5, digest); diff --git a/core/fpdfapi/parser/cpdf_security_handler.h b/core/fpdfapi/parser/cpdf_security_handler.h index 15be505705..0ae2cfe66c 100644 --- a/core/fpdfapi/parser/cpdf_security_handler.h +++ b/core/fpdfapi/parser/cpdf_security_handler.h @@ -95,7 +95,7 @@ class CPDF_SecurityHandler { int m_Version; int m_Revision; UnownedPtr m_pEncryptDict; - UnownedPtr m_pIdArray; + ByteString m_FileId; uint32_t m_Permissions; int m_Cipher; uint8_t m_EncryptKey[32]; -- cgit v1.2.3