rtld_next broke?
Timo Teras
timo.teras at iki.fi
Fri Nov 2 06:52:39 UTC 2012
On Thu, 1 Nov 2012 21:13:32 +0200 Timo Teras <timo.teras at iki.fi> wrote:
> I noticed that dlsym(RTLD_NEXT) seems to be broken under certain
> conditions. I also noticed that Floarian observed this earlier too
> [1], but no solution seems to have been provided.
>
> It appears this is related closely to the linking order of the final
> executable.
>[snip]
>
> Appears that we need to add some sort of for loop iterating through
> all the following modules.
>
> Will try to patch tomorrow. Or does someone have a better solution for
> this?
I'm now playing with the following patch. Fixes my trivial test case.
--- a/ldso/libdl/libdl.c
+++ b/ldso/libdl/libdl.c
@@ -671,7 +671,7 @@
{
struct elf_resolve *tpnt, *tfrom;
struct dyn_elf *handle;
- ElfW(Addr) from;
+ ElfW(Addr) from = 0;
struct dyn_elf *rpnt;
void *ret;
struct symbol_ref sym_ref = { NULL, NULL };
@@ -729,7 +729,13 @@
tpnt = NULL;
if (handle == _dl_symbol_tables)
tpnt = handle->dyn; /* Only search RTLD_GLOBAL objs if global object */
- ret = _dl_find_hash(name2, &handle->dyn->symbol_scope, tpnt, ELF_RTYPE_CLASS_DLSYM, &sym_ref);
+
+ do {
+ ret = _dl_find_hash(name2, &handle->dyn->symbol_scope, tpnt, ELF_RTYPE_CLASS_DLSYM, &sym_ref);
+ if (ret != NULL)
+ break;
+ handle = handle->next;
+ } while (from && handle);
#if defined(USE_TLS) && USE_TLS && defined SHARED
if (sym_ref.sym && (ELF_ST_TYPE(sym_ref.sym->st_info) == STT_TLS) && (sym_ref.tpnt)) {
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