Properly handle empty map after read-only map.
Recently, the maps for an elf in memory might show up looking like:
f0000-f1000 0 r-- /system/lib/libc.so
f1000-f2000 0 ---
f2000-f3000 1000 r-x /system/lib/libc.so
f3000-f4000 2000 rw- /system/lib/libc.so
The problem is that there is logic in the code that assumed that the
map before the execute map must be the read-only map. In the case
above, this is not true. Add a new prev_real_map that will point
to the previous map that is not one of these empty maps.
This will fix the backtraces that look like this:
#00 pc 0000000000050d58 /apex/com.android.runtime/lib64/bionic/libc.so!libc.so (offset 0x50000) (syscall+24) (BuildId: 5252408bf30e395d49ee270b54c77ca4)
To get rid of the !libc.so and the offset value, which is not correct.
Added new unit tests to verify this.
Added new offline test which an empty map between read-only and execute
map. Before this change, the backtraces had lines like
libc.so!libc.so (offset XXX) would be present.
Bug: 148075852
Test: Ran unit tests.
Change-Id: Ie04bfc96b8f91ed885cb1e655cf1e346efe48a45
diff --git a/libunwindstack/tests/MapInfoGetElfTest.cpp b/libunwindstack/tests/MapInfoGetElfTest.cpp
index d60b8b1..7f97814 100644
--- a/libunwindstack/tests/MapInfoGetElfTest.cpp
+++ b/libunwindstack/tests/MapInfoGetElfTest.cpp
@@ -68,7 +68,7 @@
};
TEST_F(MapInfoGetElfTest, invalid) {
- MapInfo info(nullptr, 0x1000, 0x2000, 0, PROT_READ, "");
+ MapInfo info(nullptr, nullptr, 0x1000, 0x2000, 0, PROT_READ, "");
// The map is empty, but this should still create an invalid elf object.
Elf* elf = info.GetElf(process_memory_, ARCH_ARM);
@@ -77,7 +77,7 @@
}
TEST_F(MapInfoGetElfTest, valid32) {
- MapInfo info(nullptr, 0x3000, 0x4000, 0, PROT_READ, "");
+ MapInfo info(nullptr, nullptr, 0x3000, 0x4000, 0, PROT_READ, "");
Elf32_Ehdr ehdr;
TestInitEhdr<Elf32_Ehdr>(&ehdr, ELFCLASS32, EM_ARM);
@@ -97,7 +97,7 @@
}
TEST_F(MapInfoGetElfTest, valid64) {
- MapInfo info(nullptr, 0x8000, 0x9000, 0, PROT_READ, "");
+ MapInfo info(nullptr, nullptr, 0x8000, 0x9000, 0, PROT_READ, "");
Elf64_Ehdr ehdr;
TestInitEhdr<Elf64_Ehdr>(&ehdr, ELFCLASS64, EM_AARCH64);
@@ -111,7 +111,7 @@
}
TEST_F(MapInfoGetElfTest, invalid_arch_mismatch) {
- MapInfo info(nullptr, 0x3000, 0x4000, 0, PROT_READ, "");
+ MapInfo info(nullptr, nullptr, 0x3000, 0x4000, 0, PROT_READ, "");
Elf32_Ehdr ehdr;
TestInitEhdr<Elf32_Ehdr>(&ehdr, ELFCLASS32, EM_ARM);
@@ -123,7 +123,7 @@
}
TEST_F(MapInfoGetElfTest, gnu_debugdata_init32) {
- MapInfo info(nullptr, 0x2000, 0x3000, 0, PROT_READ, "");
+ MapInfo info(nullptr, nullptr, 0x2000, 0x3000, 0, PROT_READ, "");
TestInitGnuDebugdata<Elf32_Ehdr, Elf32_Shdr>(ELFCLASS32, EM_ARM, true,
[&](uint64_t offset, const void* ptr, size_t size) {
@@ -139,7 +139,7 @@
}
TEST_F(MapInfoGetElfTest, gnu_debugdata_init64) {
- MapInfo info(nullptr, 0x5000, 0x8000, 0, PROT_READ, "");
+ MapInfo info(nullptr, nullptr, 0x5000, 0x8000, 0, PROT_READ, "");
TestInitGnuDebugdata<Elf64_Ehdr, Elf64_Shdr>(ELFCLASS64, EM_AARCH64, true,
[&](uint64_t offset, const void* ptr, size_t size) {
@@ -155,7 +155,7 @@
}
TEST_F(MapInfoGetElfTest, end_le_start) {
- MapInfo info(nullptr, 0x1000, 0x1000, 0, PROT_READ, elf_.path);
+ MapInfo info(nullptr, nullptr, 0x1000, 0x1000, 0, PROT_READ, elf_.path);
Elf32_Ehdr ehdr;
TestInitEhdr<Elf32_Ehdr>(&ehdr, ELFCLASS32, EM_ARM);
@@ -182,7 +182,7 @@
// Verify that if the offset is non-zero but there is no elf at the offset,
// that the full file is used.
TEST_F(MapInfoGetElfTest, file_backed_non_zero_offset_full_file) {
- MapInfo info(nullptr, 0x1000, 0x2000, 0x100, PROT_READ, elf_.path);
+ MapInfo info(nullptr, nullptr, 0x1000, 0x2000, 0x100, PROT_READ, elf_.path);
std::vector<uint8_t> buffer(0x1000);
memset(buffer.data(), 0, buffer.size());
@@ -211,7 +211,7 @@
// Verify that if the offset is non-zero and there is an elf at that
// offset, that only part of the file is used.
TEST_F(MapInfoGetElfTest, file_backed_non_zero_offset_partial_file) {
- MapInfo info(nullptr, 0x1000, 0x2000, 0x2000, PROT_READ, elf_.path);
+ MapInfo info(nullptr, nullptr, 0x1000, 0x2000, 0x2000, PROT_READ, elf_.path);
std::vector<uint8_t> buffer(0x4000);
memset(buffer.data(), 0, buffer.size());
@@ -241,7 +241,7 @@
// embedded elf is bigger than the initial map, the new object is larger
// than the original map size. Do this for a 32 bit elf and a 64 bit elf.
TEST_F(MapInfoGetElfTest, file_backed_non_zero_offset_partial_file_whole_elf32) {
- MapInfo info(nullptr, 0x5000, 0x6000, 0x1000, PROT_READ, elf_.path);
+ MapInfo info(nullptr, nullptr, 0x5000, 0x6000, 0x1000, PROT_READ, elf_.path);
std::vector<uint8_t> buffer(0x4000);
memset(buffer.data(), 0, buffer.size());
@@ -269,7 +269,7 @@
}
TEST_F(MapInfoGetElfTest, file_backed_non_zero_offset_partial_file_whole_elf64) {
- MapInfo info(nullptr, 0x7000, 0x8000, 0x1000, PROT_READ, elf_.path);
+ MapInfo info(nullptr, nullptr, 0x7000, 0x8000, 0x1000, PROT_READ, elf_.path);
std::vector<uint8_t> buffer(0x4000);
memset(buffer.data(), 0, buffer.size());
@@ -297,7 +297,7 @@
}
TEST_F(MapInfoGetElfTest, check_device_maps) {
- MapInfo info(nullptr, 0x7000, 0x8000, 0x1000, PROT_READ | MAPS_FLAGS_DEVICE_MAP,
+ MapInfo info(nullptr, nullptr, 0x7000, 0x8000, 0x1000, PROT_READ | MAPS_FLAGS_DEVICE_MAP,
"/dev/something");
// Create valid elf data in process memory for this to verify that only
@@ -343,7 +343,7 @@
wait = true;
// Create all of the threads and have them do the GetElf at the same time
// to make it likely that a race will occur.
- MapInfo info(nullptr, 0x7000, 0x8000, 0x1000, PROT_READ, "");
+ MapInfo info(nullptr, nullptr, 0x7000, 0x8000, 0x1000, PROT_READ, "");
for (size_t i = 0; i < kNumConcurrentThreads; i++) {
std::thread* thread = new std::thread([i, this, &wait, &info, &elf_in_threads]() {
while (wait)
@@ -373,8 +373,8 @@
// Verify that previous maps don't automatically get the same elf object.
TEST_F(MapInfoGetElfTest, prev_map_elf_not_set) {
- MapInfo info1(nullptr, 0x1000, 0x2000, 0, PROT_READ, "/not/present");
- MapInfo info2(&info1, 0x2000, 0x3000, 0, PROT_READ, elf_.path);
+ MapInfo info1(nullptr, nullptr, 0x1000, 0x2000, 0, PROT_READ, "/not/present");
+ MapInfo info2(&info1, &info1, 0x2000, 0x3000, 0, PROT_READ, elf_.path);
Elf32_Ehdr ehdr;
TestInitEhdr<Elf32_Ehdr>(&ehdr, ELFCLASS32, EM_ARM);
@@ -389,8 +389,25 @@
// Verify that a read-only map followed by a read-execute map will result
// in the same elf object in both maps.
TEST_F(MapInfoGetElfTest, read_only_followed_by_read_exec_share_elf) {
- MapInfo r_info(nullptr, 0x1000, 0x2000, 0, PROT_READ, elf_.path);
- MapInfo rw_info(&r_info, 0x2000, 0x3000, 0x1000, PROT_READ | PROT_EXEC, elf_.path);
+ MapInfo r_info(nullptr, nullptr, 0x1000, 0x2000, 0, PROT_READ, elf_.path);
+ MapInfo rw_info(&r_info, &r_info, 0x2000, 0x3000, 0x1000, PROT_READ | PROT_EXEC, elf_.path);
+
+ Elf32_Ehdr ehdr;
+ TestInitEhdr<Elf32_Ehdr>(&ehdr, ELFCLASS32, EM_ARM);
+ memory_->SetMemory(0x1000, &ehdr, sizeof(ehdr));
+ Elf* elf = rw_info.GetElf(process_memory_, ARCH_ARM);
+ ASSERT_TRUE(elf != nullptr);
+ ASSERT_TRUE(elf->valid());
+
+ ASSERT_EQ(elf, r_info.GetElf(process_memory_, ARCH_ARM));
+}
+
+// Verify that a read-only map followed by an empty map, then followed by
+// a read-execute map will result in the same elf object in both maps.
+TEST_F(MapInfoGetElfTest, read_only_followed_by_empty_then_read_exec_share_elf) {
+ MapInfo r_info(nullptr, nullptr, 0x1000, 0x2000, 0, PROT_READ, elf_.path);
+ MapInfo empty(&r_info, &r_info, 0x2000, 0x3000, 0, 0, "");
+ MapInfo rw_info(&empty, &r_info, 0x3000, 0x4000, 0x2000, PROT_READ | PROT_EXEC, elf_.path);
Elf32_Ehdr ehdr;
TestInitEhdr<Elf32_Ehdr>(&ehdr, ELFCLASS32, EM_ARM);