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
This commit is contained in:
Yabin Cui 2015-04-14 10:27:54 -07:00
parent e83d8a6900
commit 03dca28def
1 changed files with 4 additions and 2 deletions

View File

@ -29,6 +29,8 @@
#include "elf_utils.h"
#define NOTE_ALIGN(size) ((size + 3) & ~3)
template <typename HdrType, typename PhdrType, typename NhdrType>
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;