Be permissive about badly formed elf files.
Here is the allowable issues with an elf file that will not result in an error:
- The program headers/section headers offset points to unreadable memory.
- Allow missing program header and/or section headers.
- Allow a symbol table section header to point to invalid symbol table values.
There is no real reason to require the elf file be perfect. Everything in
the code has sane defaults, so any missing information won't cause any
problems.
This gets rid of the warning that occurs any time an elf is loaded
from memory. In memory elf files never contain all of the section headers,
and do not contain the symbol table data.
Update tests to test these new cases.
Test: Builds and unit tests all pass.
Change-Id: Iaefe2cd6b6c965a01ed425a112d6afae339f3b78
diff --git a/libunwindstack/tests/ElfInterfaceTest.cpp b/libunwindstack/tests/ElfInterfaceTest.cpp
index aa6df84..9326bff 100644
--- a/libunwindstack/tests/ElfInterfaceTest.cpp
+++ b/libunwindstack/tests/ElfInterfaceTest.cpp
@@ -97,9 +97,15 @@
template <typename ElfType>
void InitHeadersDebugFrameFail();
+ template <typename Ehdr, typename Phdr, typename ElfInterfaceType>
+ void InitProgramHeadersMalformed();
+
template <typename Ehdr, typename Shdr, typename ElfInterfaceType>
void InitSectionHeadersMalformed();
+ template <typename Ehdr, typename Shdr, typename ElfInterfaceType>
+ void InitSectionHeadersMalformedSymData();
+
template <typename Ehdr, typename Shdr, typename Sym, typename ElfInterfaceType>
void InitSectionHeaders(uint64_t entry_size);
@@ -677,6 +683,29 @@
InitHeadersDebugFrame<ElfInterface64Fake>();
}
+template <typename Ehdr, typename Phdr, typename ElfInterfaceType>
+void ElfInterfaceTest::InitProgramHeadersMalformed() {
+ std::unique_ptr<ElfInterfaceType> elf(new ElfInterfaceType(&memory_));
+
+ Ehdr ehdr = {};
+ ehdr.e_phoff = 0x100;
+ ehdr.e_phnum = 3;
+ ehdr.e_phentsize = sizeof(Phdr);
+ memory_.SetMemory(0, &ehdr, sizeof(ehdr));
+
+ uint64_t load_bias = 0;
+ ASSERT_TRUE(elf->Init(&load_bias));
+ EXPECT_EQ(0U, load_bias);
+}
+
+TEST_F(ElfInterfaceTest, init_program_headers_malformed32) {
+ InitProgramHeadersMalformed<Elf32_Ehdr, Elf32_Phdr, ElfInterface32>();
+}
+
+TEST_F(ElfInterfaceTest, init_program_headers_malformed64) {
+ InitProgramHeadersMalformed<Elf64_Ehdr, Elf64_Phdr, ElfInterface64>();
+}
+
template <typename Ehdr, typename Shdr, typename ElfInterfaceType>
void ElfInterfaceTest::InitSectionHeadersMalformed() {
std::unique_ptr<ElfInterfaceType> elf(new ElfInterfaceType(&memory_));
@@ -700,6 +729,80 @@
InitSectionHeadersMalformed<Elf64_Ehdr, Elf64_Shdr, ElfInterface64>();
}
+template <typename Ehdr, typename Shdr, typename ElfInterfaceType>
+void ElfInterfaceTest::InitSectionHeadersMalformedSymData() {
+ std::unique_ptr<ElfInterfaceType> elf(new ElfInterfaceType(&memory_));
+
+ uint64_t offset = 0x1000;
+
+ Ehdr ehdr = {};
+ ehdr.e_shoff = offset;
+ ehdr.e_shnum = 5;
+ ehdr.e_shentsize = sizeof(Shdr);
+ memory_.SetMemory(0, &ehdr, sizeof(ehdr));
+
+ offset += ehdr.e_shentsize;
+
+ Shdr shdr = {};
+ shdr.sh_type = SHT_SYMTAB;
+ shdr.sh_link = 4;
+ shdr.sh_addr = 0x5000;
+ shdr.sh_offset = 0x5000;
+ shdr.sh_entsize = 0x100;
+ shdr.sh_size = shdr.sh_entsize * 10;
+ memory_.SetMemory(offset, &shdr, sizeof(shdr));
+ offset += ehdr.e_shentsize;
+
+ memset(&shdr, 0, sizeof(shdr));
+ shdr.sh_type = SHT_DYNSYM;
+ shdr.sh_link = 10;
+ shdr.sh_addr = 0x6000;
+ shdr.sh_offset = 0x6000;
+ shdr.sh_entsize = 0x100;
+ shdr.sh_size = shdr.sh_entsize * 10;
+ memory_.SetMemory(offset, &shdr, sizeof(shdr));
+ offset += ehdr.e_shentsize;
+
+ memset(&shdr, 0, sizeof(shdr));
+ shdr.sh_type = SHT_DYNSYM;
+ shdr.sh_link = 2;
+ shdr.sh_addr = 0x6000;
+ shdr.sh_offset = 0x6000;
+ shdr.sh_entsize = 0x100;
+ shdr.sh_size = shdr.sh_entsize * 10;
+ memory_.SetMemory(offset, &shdr, sizeof(shdr));
+ offset += ehdr.e_shentsize;
+
+ // The string data for the entries.
+ memset(&shdr, 0, sizeof(shdr));
+ shdr.sh_type = SHT_STRTAB;
+ shdr.sh_name = 0x20000;
+ shdr.sh_offset = 0xf000;
+ shdr.sh_size = 0x1000;
+ memory_.SetMemory(offset, &shdr, sizeof(shdr));
+ offset += ehdr.e_shentsize;
+
+ uint64_t load_bias = 0;
+ ASSERT_TRUE(elf->Init(&load_bias));
+ EXPECT_EQ(0U, load_bias);
+ EXPECT_EQ(0U, elf->debug_frame_offset());
+ EXPECT_EQ(0U, elf->debug_frame_size());
+ EXPECT_EQ(0U, elf->gnu_debugdata_offset());
+ EXPECT_EQ(0U, elf->gnu_debugdata_size());
+
+ std::string name;
+ uint64_t name_offset;
+ ASSERT_FALSE(elf->GetFunctionName(0x90010, &name, &name_offset));
+}
+
+TEST_F(ElfInterfaceTest, init_section_headers_malformed_symdata32) {
+ InitSectionHeadersMalformedSymData<Elf32_Ehdr, Elf32_Shdr, ElfInterface32>();
+}
+
+TEST_F(ElfInterfaceTest, init_section_headers_malformed_symdata64) {
+ InitSectionHeadersMalformedSymData<Elf64_Ehdr, Elf64_Shdr, ElfInterface64>();
+}
+
template <typename Ehdr, typename Shdr, typename Sym, typename ElfInterfaceType>
void ElfInterfaceTest::InitSectionHeaders(uint64_t entry_size) {
std::unique_ptr<ElfInterfaceType> elf(new ElfInterfaceType(&memory_));
@@ -708,7 +811,7 @@
Ehdr ehdr = {};
ehdr.e_shoff = offset;
- ehdr.e_shnum = 10;
+ ehdr.e_shnum = 5;
ehdr.e_shentsize = entry_size;
memory_.SetMemory(0, &ehdr, sizeof(ehdr));
@@ -795,7 +898,7 @@
Ehdr ehdr = {};
ehdr.e_shoff = offset;
- ehdr.e_shnum = 10;
+ ehdr.e_shnum = 6;
ehdr.e_shentsize = sizeof(Shdr);
ehdr.e_shstrndx = 2;
memory_.SetMemory(0, &ehdr, sizeof(ehdr));