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Fix some shadow variables, including one in file_id.cc that causes all files to generate the same hash. Add a test to make sure this doesn't happen again.

Browse source 
Review URL: http://breakpad.appspot.com/316002

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@875 4c0a9323-5329-0410-9bdc-e9ce6186880e
This commit is contained in:
thestig@chromium.org 2011-10-20 18:23:01 +00:00
parent 70698339f6
commit 11582abc27
6 changed files with 127 additions and 30 deletions
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18
src/common/linux/file_id.cc
View file

@ -107,10 +107,10 @@ static void FindElfClassSection(const char *elf_base,
const Shdr* section = NULL;
for (int i = 0; i < elf_header->e_shnum; ++i) {
if (sections[i].sh_type == section_type) {
const char* section_name = (char*)(elf_base +
string_section->sh_offset +
sections[i].sh_name);
if (!my_strncmp(section_name, section_name, name_len)) {
const char* current_section_name = (char*)(elf_base +
string_section->sh_offset +
sections[i].sh_name);
if (!my_strncmp(current_section_name, section_name, name_len)) {
section = &sections[i];
break;
}
@ -166,8 +166,7 @@ static bool FindElfSection(const void *elf_mapped_base,
template<typename ElfClass>
static bool ElfClassBuildIDNoteIdentifier(const void *section,
uint8_t identifier[kMDGUIDSize])
{
uint8_t identifier[kMDGUIDSize]) {
typedef typename ElfClass::Nhdr Nhdr;
const Nhdr* note_header = reinterpret_cast<const Nhdr*>(section);
@ -190,8 +189,7 @@ static bool ElfClassBuildIDNoteIdentifier(const void *section,
// Attempt to locate a .note.gnu.build-id section in an ELF binary
// and copy as many bytes of it as will fit into |identifier|.
static bool FindElfBuildIDNote(const void *elf_mapped_base,
uint8_t identifier[kMDGUIDSize])
{
uint8_t identifier[kMDGUIDSize]) {
void* note_section;
int note_size, elfclass;
if (!FindElfSection(elf_mapped_base, ".note.gnu.build-id", SHT_NOTE,
@ -213,7 +211,6 @@ static bool FindElfBuildIDNote(const void *elf_mapped_base,
// a simple hash by XORing the first page worth of bytes into |identifier|.
static bool HashElfTextSection(const void *elf_mapped_base,
uint8_t identifier[kMDGUIDSize]) {
void* text_section;
int text_size;
if (!FindElfSection(elf_mapped_base, ".text", SHT_PROGBITS,
@ -235,8 +232,7 @@ static bool HashElfTextSection(const void *elf_mapped_base,
// static
bool FileID::ElfFileIdentifierFromMappedFile(void* base,
uint8_t identifier[kMDGUIDSize])
{
uint8_t identifier[kMDGUIDSize]) {
// Look for a build id note first.
if (FindElfBuildIDNote(base, identifier))
return true;

101
src/common/linux/file_id_unittest.cc
View file

@ -43,6 +43,18 @@ using google_breakpad::synth_elf::ELF;
using google_breakpad::test_assembler::kLittleEndian;
using google_breakpad::test_assembler::Section;
namespace {
// Simply calling Section::Append(size, byte) produces a uninteresting pattern
// that tends to get hashed to 0000...0000. This populates the section with
// data to produce better hashes.
void PopulateSection(Section* section, int size, int prime_number) {
for (int i = 0; i < size; i++)
section->Append(1, (i % prime_number) % 256);
}
} // namespace
TEST(FileIDStripTest, StripSelf) {
// Calculate the File ID of this binary using
// FileID::ElfFileIdentifier, then make a copy of this binary,
@ -181,3 +193,92 @@ TEST_F(FileIDTest, BuildID) {
sizeof(identifier_string));
EXPECT_STREQ(expected_identifier_string, identifier_string);
}
// Test to make sure two files with different text sections produce
// different hashes when not using a build id.
TEST_F(FileIDTest, UniqueHashes32) {
char identifier_string_1[] =
"00000000-0000-0000-0000-000000000000";
char identifier_string_2[] =
"00000000-0000-0000-0000-000000000000";
uint8_t identifier_1[sizeof(MDGUID)];
uint8_t identifier_2[sizeof(MDGUID)];
{
ELF elf1(EM_386, ELFCLASS32, kLittleEndian);
Section foo_1(kLittleEndian);
PopulateSection(&foo_1, 32, 5);
elf1.AddSection(".foo", foo_1, SHT_PROGBITS);
Section text_1(kLittleEndian);
PopulateSection(&text_1, 4096, 17);
elf1.AddSection(".text", text_1, SHT_PROGBITS);
elf1.Finish();
GetElfContents(elf1);
}
EXPECT_TRUE(FileID::ElfFileIdentifierFromMappedFile(elfdata, identifier_1));
FileID::ConvertIdentifierToString(identifier_1, identifier_string_1,
sizeof(identifier_string_1));
{
ELF elf2(EM_386, ELFCLASS32, kLittleEndian);
Section text_2(kLittleEndian);
Section foo_2(kLittleEndian);
PopulateSection(&foo_2, 32, 5);
elf2.AddSection(".foo", foo_2, SHT_PROGBITS);
PopulateSection(&text_2, 4096, 31);
elf2.AddSection(".text", text_2, SHT_PROGBITS);
elf2.Finish();
GetElfContents(elf2);
}
EXPECT_TRUE(FileID::ElfFileIdentifierFromMappedFile(elfdata, identifier_2));
FileID::ConvertIdentifierToString(identifier_2, identifier_string_2,
sizeof(identifier_string_2));
EXPECT_STRNE(identifier_string_1, identifier_string_2);
}
// Same as UniqueHashes32, for x86-64.
TEST_F(FileIDTest, UniqueHashes64) {
char identifier_string_1[] =
"00000000-0000-0000-0000-000000000000";
char identifier_string_2[] =
"00000000-0000-0000-0000-000000000000";
uint8_t identifier_1[sizeof(MDGUID)];
uint8_t identifier_2[sizeof(MDGUID)];
{
ELF elf1(EM_X86_64, ELFCLASS64, kLittleEndian);
Section foo_1(kLittleEndian);
PopulateSection(&foo_1, 32, 5);
elf1.AddSection(".foo", foo_1, SHT_PROGBITS);
Section text_1(kLittleEndian);
PopulateSection(&text_1, 4096, 17);
elf1.AddSection(".text", text_1, SHT_PROGBITS);
elf1.Finish();
GetElfContents(elf1);
}
EXPECT_TRUE(FileID::ElfFileIdentifierFromMappedFile(elfdata, identifier_1));
FileID::ConvertIdentifierToString(identifier_1, identifier_string_1,
sizeof(identifier_string_1));
{
ELF elf2(EM_X86_64, ELFCLASS64, kLittleEndian);
Section text_2(kLittleEndian);
Section foo_2(kLittleEndian);
PopulateSection(&foo_2, 32, 5);
elf2.AddSection(".foo", foo_2, SHT_PROGBITS);
PopulateSection(&text_2, 4096, 31);
elf2.AddSection(".text", text_2, SHT_PROGBITS);
elf2.Finish();
GetElfContents(elf2);
}
EXPECT_TRUE(FileID::ElfFileIdentifierFromMappedFile(elfdata, identifier_2));
FileID::ConvertIdentifierToString(identifier_2, identifier_string_2,
sizeof(identifier_string_2));
EXPECT_STRNE(identifier_string_1, identifier_string_2);
}