From 03dca28def9303467ec6f28d43e90d465b816475 Mon Sep 17 00:00:00 2001 From: Yabin Cui Date: Tue, 14 Apr 2015 10:27:54 -0700 Subject: [PATCH] Fix alignment when reading note segment. ELF said that padding is present, if necessary, to ensure 4-byte alignment for the descriptor and next note entry, but such padding is not included in namesz and descsz. Change-Id: I7896783f3d9a787772d56c49905f52a493c9fba1 --- debuggerd/elf_utils.cpp | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/debuggerd/elf_utils.cpp b/debuggerd/elf_utils.cpp index 764b9db86..5ea03e752 100644 --- a/debuggerd/elf_utils.cpp +++ b/debuggerd/elf_utils.cpp @@ -29,6 +29,8 @@ #include "elf_utils.h" +#define NOTE_ALIGN(size) ((size + 3) & ~3) + template static bool get_build_id( Backtrace* backtrace, uintptr_t base_addr, uint8_t* e_ident, std::string* build_id) { @@ -60,7 +62,7 @@ static bool get_build_id( addr += sizeof(nhdr); if (nhdr.n_type == NT_GNU_BUILD_ID) { // Skip the name (which is the owner and should be "GNU"). - addr += nhdr.n_namesz; + addr += NOTE_ALIGN(nhdr.n_namesz); uint8_t build_id_data[128]; if (nhdr.n_namesz > sizeof(build_id_data)) { ALOGE("Possible corrupted note, name size value is too large: %u", @@ -80,7 +82,7 @@ static bool get_build_id( } else { // Move past the extra note data. hdr_size -= sizeof(nhdr); - size_t skip_bytes = nhdr.n_namesz + nhdr.n_descsz; + size_t skip_bytes = NOTE_ALIGN(nhdr.n_namesz) + NOTE_ALIGN(nhdr.n_descsz); addr += skip_bytes; if (hdr_size < skip_bytes) { break;