Fix off-by-one in ReadBuildIDFromMemory.
This was sometimes causing build ids to be truncated, probably because
of memory corruption in std::string. A similar off-by-one was fixed in
ReadBuildID in aosp/939619.
Bug: 129873279
Change-Id: I401fe7f991dbd135f5b4836381b48ea3c6a2243f
diff --git a/libunwindstack/ElfInterface.cpp b/libunwindstack/ElfInterface.cpp
index 341275d..821e042 100644
--- a/libunwindstack/ElfInterface.cpp
+++ b/libunwindstack/ElfInterface.cpp
@@ -662,7 +662,7 @@
if (note_size - offset < hdr.n_descsz || hdr.n_descsz == 0) {
return "";
}
- std::string build_id(hdr.n_descsz - 1, '\0');
+ std::string build_id(hdr.n_descsz, '\0');
if (memory->ReadFully(note_offset + offset, &build_id[0], hdr.n_descsz)) {
return build_id;
}
diff --git a/libunwindstack/tests/MapInfoGetBuildIDTest.cpp b/libunwindstack/tests/MapInfoGetBuildIDTest.cpp
index 6953e26..70e136b 100644
--- a/libunwindstack/tests/MapInfoGetBuildIDTest.cpp
+++ b/libunwindstack/tests/MapInfoGetBuildIDTest.cpp
@@ -142,15 +142,14 @@
char note_section[128];
Elf32_Nhdr note_header = {};
- note_header.n_namesz = 4; // "GNU"
- note_header.n_descsz = 12; // "ELF_BUILDID"
+ note_header.n_namesz = sizeof("GNU");
+ note_header.n_descsz = sizeof("ELF_BUILDID") - 1;
note_header.n_type = NT_GNU_BUILD_ID;
memcpy(¬e_section, ¬e_header, sizeof(note_header));
size_t note_offset = sizeof(note_header);
- memcpy(¬e_section[note_offset], "GNU", sizeof("GNU"));
- note_offset += sizeof("GNU");
- memcpy(¬e_section[note_offset], "ELF_BUILDID", sizeof("ELF_BUILDID"));
- note_offset += sizeof("ELF_BUILDID");
+ memcpy(¬e_section[note_offset], "GNU", note_header.n_namesz);
+ note_offset += note_header.n_namesz;
+ memcpy(¬e_section[note_offset], "ELF_BUILDID", note_header.n_descsz);
Elf32_Shdr shdr = {};
shdr.sh_type = SHT_NOTE;
@@ -195,4 +194,10 @@
MultipleThreadTest("ELF_BUILDID");
}
+TEST_F(MapInfoGetBuildIDTest, real_elf) {
+ MapInfo map_info(nullptr, nullptr, 0x1000, 0x20000, 0, PROT_READ | PROT_WRITE,
+ TestGetFileDirectory() + "offline/empty_arm64/libc.so");
+ EXPECT_EQ("6df0590c4920f4c7b9f34fe833f37d54", map_info.GetPrintableBuildID());
+}
+
} // namespace unwindstack