From bc5949fd4f8cddf4eee74492c86a8a72f4dee0e7 Mon Sep 17 00:00:00 2001 From: Leonid Lisovskiy Date: Mon, 20 Jun 2016 20:29:45 +0300 Subject: ldso: fix dlsym hang when reloading DSOs It can happen under certain cases that the DSO had refcount 0, but was already loaded. (NODELETE flag is set, or it is pulled in via both NEEDED dependency and explicit dlopen()). Add extra reference count for NODELETE objects, this will ensure that the reference count never drops below one. It is improved version of http://lists.busybox.net/pipermail/uclibc/2013-June/047826.html Signed-off-by: Leonid Lisovskiy --- ldso/ldso/dl-elf.c | 2 ++ ldso/libdl/libdl.c | 4 ++-- 2 files changed, 4 insertions(+), 2 deletions(-) (limited to 'ldso') diff --git a/ldso/ldso/dl-elf.c b/ldso/ldso/dl-elf.c index 8f71aeb05..a046aeb74 100644 --- a/ldso/ldso/dl-elf.c +++ b/ldso/ldso/dl-elf.c @@ -884,6 +884,8 @@ struct elf_resolve *_dl_load_elf_shared_library(unsigned int rflags, #endif (*rpnt)->dyn = tpnt; tpnt->usage_count++; + if (tpnt->rtld_flags & RTLD_NODELETE) + tpnt->usage_count++; #ifdef __LDSO_STANDALONE_SUPPORT__ tpnt->libtype = (epnt->e_type == ET_DYN) ? elf_lib : elf_executable; #else diff --git a/ldso/libdl/libdl.c b/ldso/libdl/libdl.c index 489c78759..0cf3b7037 100644 --- a/ldso/libdl/libdl.c +++ b/ldso/libdl/libdl.c @@ -818,7 +818,7 @@ static int do_dlclose(void *vhandle, int need_fini) _dl_handles = rpnt->next_handle; _dl_if_debug_print("%s: usage count: %d\n", handle->dyn->libname, handle->dyn->usage_count); - if (handle->dyn->usage_count != 1 || (handle->dyn->rtld_flags & RTLD_NODELETE)) { + if (handle->dyn->usage_count != 1) { handle->dyn->usage_count--; free(handle); return 0; @@ -840,7 +840,7 @@ static int do_dlclose(void *vhandle, int need_fini) for (j = 0; j < handle->init_fini.nlist; ++j) { tpnt = handle->init_fini.init_fini[j]; tpnt->usage_count--; - if (tpnt->usage_count == 0 && !(tpnt->rtld_flags & RTLD_NODELETE)) { + if (tpnt->usage_count == 0) { if ((tpnt->dynamic_info[DT_FINI] || tpnt->dynamic_info[DT_FINI_ARRAY]) && need_fini -- cgit v1.2.3