Revert "Revert "bionic/linker: fix symbol lookup during relocations""
This reverts commit 33acbf0719c4f3db059bc9e1f52cf554a5d0295f.
diff --git a/linker/linker.c b/linker/linker.c
index eed9738..6f09837 100644
--- a/linker/linker.c
+++ b/linker/linker.c
@@ -87,6 +87,12 @@
static soinfo *solist = &libdl_info;
static soinfo *sonext = &libdl_info;
+static inline int validate_soinfo(soinfo *si)
+{
+ return (si >= sopool && si < sopool + SO_MAX) ||
+ si == &libdl_info;
+}
+
static char ldpaths_buf[LDPATH_BUFSIZE];
static const char *ldpaths[LDPATH_MAX + 1];
@@ -421,32 +427,70 @@
return _elf_lookup (si, *elf_hash, name);
}
-/* This is used by dl_sym() */
+static Elf32_Sym *
+_do_lookup(soinfo *si, const char *name, unsigned *base)
+{
+ unsigned elf_hash = 0;
+ Elf32_Sym *s;
+ unsigned *d;
+ soinfo *lsi = si;
+
+ /* Look for symbols in the local scope first (the object who is
+ * searching). This happens with C++ templates on i386 for some
+ * reason. */
+ s = _do_lookup_in_so(si, name, &elf_hash);
+ if(s != NULL)
+ goto done;
+
+ for(d = si->dynamic; *d; d += 2) {
+ if(d[0] == DT_NEEDED){
+ lsi = (soinfo *)d[1];
+ if (!validate_soinfo(lsi)) {
+ DL_ERR("%5d bad DT_NEEDED pointer in %s",
+ pid, si->name);
+ return 0;
+ }
+
+ DEBUG("%5d %s: looking up %s in %s\n",
+ pid, si->name, name, lsi->name);
+ s = _do_lookup_in_so(lsi, name, &elf_hash);
+ if(s != NULL)
+ goto done;
+ }
+ }
+
+done:
+ if(s != NULL) {
+ TRACE_TYPE(LOOKUP, "%5d si %s sym %s s->st_value = 0x%08x, "
+ "found in %s, base = 0x%08x\n",
+ pid, si->name, name, s->st_value, lsi->name, lsi->base);
+ *base = lsi->base;
+ return s;
+ }
+
+ return 0;
+}
+
+/* This is used by dl_sym(). It performs symbol lookup only within the
+ specified soinfo object and not in any of its dependencies.
+ */
Elf32_Sym *lookup_in_library(soinfo *si, const char *name)
{
unsigned unused = 0;
return _do_lookup_in_so(si, name, &unused);
}
-static Elf32_Sym *
-_do_lookup(soinfo *user_si, const char *name, unsigned *base)
+/* This is used by dl_sym(). It performs a global symbol lookup.
+ */
+Elf32_Sym *lookup(const char *name, unsigned *base)
{
unsigned elf_hash = 0;
Elf32_Sym *s = NULL;
soinfo *si;
- /* Look for symbols in the local scope first (the object who is
- * searching). This happens with C++ templates on i386 for some
- * reason. */
- if (user_si) {
- s = _do_lookup_in_so(user_si, name, &elf_hash);
- if (s != NULL)
- *base = user_si->base;
- }
-
for(si = solist; (s == NULL) && (si != NULL); si = si->next)
{
- if((si->flags & FLAG_ERROR) || (si == user_si))
+ if(si->flags & FLAG_ERROR)
continue;
s = _do_lookup_in_so(si, name, &elf_hash);
if (s != NULL) {
@@ -455,7 +499,7 @@
}
}
- if (s != NULL) {
+ if(s != NULL) {
TRACE_TYPE(LOOKUP, "%5d %s s->st_value = 0x%08x, "
"si->base = 0x%08x\n", pid, name, s->st_value, si->base);
return s;
@@ -464,12 +508,6 @@
return 0;
}
-/* This is used by dl_sym() */
-Elf32_Sym *lookup(const char *name, unsigned *base)
-{
- return _do_lookup(NULL, name, base);
-}
-
#if 0
static void dump(soinfo *si)
{
@@ -1116,14 +1154,16 @@
for(d = si->dynamic; *d; d += 2) {
if(d[0] == DT_NEEDED){
- TRACE("%5d %s needs to unload %s\n", pid,
- si->name, si->strtab + d[1]);
- soinfo *lsi = find_library(si->strtab + d[1]);
- if(lsi)
+ soinfo *lsi = (soinfo *)d[1];
+ d[1] = 0;
+ if (validate_soinfo(lsi)) {
+ TRACE("%5d %s needs to unload %s\n", pid,
+ si->name, lsi->name);
unload_library(lsi);
+ }
else
- DL_ERR("%5d could not unload '%s'",
- pid, si->strtab + d[1]);
+ DL_ERR("%5d %s: could not unload dependent library",
+ pid, si->name);
}
}
@@ -1641,6 +1681,14 @@
pid, si->strtab + d[1], si->name, tmp_err_buf);
goto fail;
}
+ /* Save the soinfo of the loaded DT_NEEDED library in the payload
+ of the DT_NEEDED entry itself, so that we can retrieve the
+ soinfo directly later from the dynamic segment. This is a hack,
+ but it allows us to map from DT_NEEDED to soinfo efficiently
+ later on when we resolve relocations, trying to look up a symgol
+ with dlsym().
+ */
+ d[1] = (unsigned)lsi;
lsi->refcount++;
}
}