Fix logic in loading dependencies crossing namespace boundaries

This change addresses multiple problems introduced by
02586a2a34e6acfccf359b94db840f422b6c0231

1. In the case of unsuccessful dlopen the failure guard is triggered
for two namespaces which leads to double unload.

2. In the case where load_tasks includes libraries from 3 and more
namespaces it results in incorrect linking of libraries shared between
second and third/forth and so on namespaces.

The root cause of these problems was recursive call to find_libraries.
It does not do what it is expected to do. It does not form new load_tasks
list and immediately jumps to linking local_group. Not only this skips
reference counting it also will include unlinked but accessible library
from third (and fourth and fifth) namespaces in invalid local group. The
best case scenario here is that for 3 or more namesapces this will
fail to link. The worse case scenario it will link the library
incorrectly with will lead to very hard to catch bugs.

This change removes recursive call and replaces it with explicit list of
local_groups which should be linked. It also revisits the way we do
reference counting - with this change the reference counts are updated after
after libraries are successfully loaded.

Also update soinfo_free to abort in case when linker tries to free same
soinfo for the second time - this makes linker behavior less undefined.

Test: bionic-unit-tests
Bug: http://b/69787209
Change-Id: Iea25ced181a98c6503cce6e2b832c91d697342d5

1 files changed, 0 insertions, 4 deletions

diff --git a/linker/linker_main.cpp b/linker/linker_main.cpp
index 317f0d29b..dc1fa7550 100644
--- a/linker/linker_main.cpp
+++ b/linker/linker_main.cpp
@@ -384,9 +384,6 @@ static ElfW(Addr) __linker_init_post_relocation(KernelArgumentBlock& args) {
   const char** needed_library_names = &needed_library_name_list[0];
   size_t needed_libraries_count = needed_library_name_list.size();
 
-  // readers_map is shared across recursive calls to find_libraries so that we
-  // don't need to re-load elf headers.
-  std::unordered_map<const soinfo*, ElfReader> readers_map;
   if (needed_libraries_count > 0 &&
       !find_libraries(&g_default_namespace,
                       si,
@@ -399,7 +396,6 @@ static ElfW(Addr) __linker_init_post_relocation(KernelArgumentBlock& args) {
                       nullptr,
                       true /* add_as_children */,
                       true /* search_linked_namespaces */,
-                      readers_map,
                       &namespaces)) {
     __linker_cannot_link(g_argv[0]);
   } else if (needed_libraries_count == 0) {