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Fix unused DT entry warnings.

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DT_STRSZ Implement strtab boundary checks
 DT_FLAGS_1 Warn if flags other than DF_1_NOW|DF_1_GLOBAL are set

Bug: 17552334
Change-Id: Iaad29cd52f5b2d7d2f785fb351697906dc1617d9
This commit is contained in:
Dmitriy Ivanov
2014-09-29 19:14:45 -07:00
parent 9997daa0ff
commit 6cdeb5234d
4 changed files with 66 additions and 9 deletions
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34
linker/linker.cpp
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@@ -417,14 +417,13 @@ int dl_iterate_phdr(int (*cb)(dl_phdr_info* info, size_t size, void* data), void
static ElfW(Sym)* soinfo_elf_lookup(soinfo* si, unsigned hash, const char* name) {
ElfW(Sym)* symtab = si->symtab;
const char* strtab = si->strtab;
TRACE_TYPE(LOOKUP, "SEARCH %s in %s@%p %x %zd",
name, si->name, reinterpret_cast<void*>(si->base), hash, hash % si->nbucket);
for (unsigned n = si->bucket[hash % si->nbucket]; n != 0; n = si->chain[n]) {
ElfW(Sym)* s = symtab + n;
if (strcmp(strtab + s->st_name, name)) continue;
if (strcmp(si->get_string(s->st_name), name)) continue;
// only concern ourselves with global and weak symbol definitions
switch (ELF_ST_BIND(s->st_info)) {
@@ -775,7 +774,7 @@ template<typename F>
static void for_each_dt_needed(const soinfo* si, F action) {
for (ElfW(Dyn)* d = si->dynamic; d->d_tag != DT_NULL; ++d) {
if (d->d_tag == DT_NEEDED) {
action(si->strtab + d->d_un.d_val);
action(si->get_string(d->d_un.d_val));
}
}
}
@@ -1085,7 +1084,7 @@ int soinfo::Relocate(ElfW(Rela)* rela, unsigned count) {
soinfo* lsi = nullptr;
if (sym != 0) {
sym_name = reinterpret_cast<const char*>(strtab + symtab[sym].st_name);
sym_name = get_string(symtab[sym].st_name);
s = soinfo_do_lookup(this, sym_name, &lsi);
if (s == nullptr) {
// We only allow an undefined symbol if this is a weak reference...
@@ -1363,7 +1362,7 @@ int soinfo::Relocate(ElfW(Rel)* rel, unsigned count) {
soinfo* lsi = nullptr;
if (sym != 0) {
sym_name = reinterpret_cast<const char*>(strtab + symtab[sym].st_name);
sym_name = get_string(symtab[sym].st_name);
s = soinfo_do_lookup(this, sym_name, &lsi);
if (s == nullptr) {
// We only allow an undefined symbol if this is a weak reference...
@@ -1581,7 +1580,7 @@ static bool mips_relocate_got(soinfo* si) {
got = si->plt_got + local_gotno;
for (size_t g = gotsym; g < symtabno; g++, sym++, got++) {
// This is an undefined reference... try to locate it.
const char* sym_name = si->strtab + sym->st_name;
const char* sym_name = si->get_string(sym->st_name);
soinfo* lsi = nullptr;
ElfW(Sym)* s = soinfo_do_lookup(si, sym_name, &lsi);
if (s == nullptr) {
@@ -1787,6 +1786,14 @@ ElfW(Addr) soinfo::resolve_symbol_address(ElfW(Sym)* s) {
return static_cast<ElfW(Addr)>(s->st_value + load_bias);
}
const char* soinfo::get_string(ElfW(Word) index) const {
if (has_min_version(1) && (index >= strtab_size)) {
__libc_fatal("%s: strtab out of bounds error; STRSZ=%zd, name=%d", name, strtab_size, index);
}
return strtab + index;
}
/* Force any of the closed stdin, stdout and stderr to be associated with
/dev/null. */
static int nullify_closed_stdio() {
@@ -1895,6 +1902,9 @@ bool soinfo::PrelinkImage() {
case DT_STRTAB:
strtab = reinterpret_cast<const char*>(load_bias + d->d_un.d_ptr);
break;
case DT_STRSZ:
strtab_size = d->d_un.d_val;
break;
case DT_SYMTAB:
symtab = reinterpret_cast<ElfW(Sym)*>(load_bias + d->d_un.d_ptr);
break;
@@ -2048,6 +2058,16 @@ bool soinfo::PrelinkImage() {
has_DT_SYMBOLIC = true;
}
break;
case DT_FLAGS_1:
if ((d->d_un.d_val & DF_1_GLOBAL) != 0) {
rtld_flags |= RTLD_GLOBAL;
}
// TODO: Implement other flags
if ((d->d_un.d_val & ~(DF_1_NOW | DF_1_GLOBAL)) != 0) {
DL_WARN("Unsupported flags DT_FLAGS_1=%p", reinterpret_cast<void*>(d->d_un.d_val));
}
break;
#if defined(__mips__)
case DT_STRSZ:
break;
@@ -2079,7 +2099,7 @@ bool soinfo::PrelinkImage() {
default:
if (!relocating_linker) {
DEBUG("%s: unused DT entry: type %p arg %p", name,
DL_WARN("%s: unused DT entry: type %p arg %p", name,
reinterpret_cast<void*>(d->d_tag), reinterpret_cast<void*>(d->d_un.d_val));
}
break;