Description wenyan xin 2020-04-29 03:29:04 EDT

In my case, there are one exective and two shared libraries.

If one global variable exports in one shared libary.

And all of the exective, shared library 1 and shared library 2 try to access the exported global variable, when access it in shared library 2, that cause the tcf-server assert and crash.

when I debug the txf-server process, I can find the assert happened at following statement in function elf_list_next in file agent/tcf/services/tcf_elf.c.

1627 ELF_File * elf_list_next(Context * ctx) {
...
1630     assert(state->ctx == ctx);    /* assert happened */

but if I changed the code as following, the issue gone.
-----------------------------

git diff --color
diff --git a/agent/tcf/services/tcf_elf.c b/agent/tcf/services/tcf_elf.c
index 9caa8ce..f15ceba 100644
--- a/agent/tcf/services/tcf_elf.c
+++ b/agent/tcf/services/tcf_elf.c
@@ -1624,6 +1624,15 @@ MemoryRegion * elf_list_region(Context * ctx) {

 ELF_File * elf_list_next(Context * ctx) {
     ElfListState * state = elf_list_state;
+
+    while (state->ctx != ctx)
+        state = state->next;
+
+    if (!state) {
+        errno = 0;
+        return NULL;
+    }
+
     assert(state != NULL);
     assert(state->ctx == ctx);
     assert(state->map.region_cnt > 0);
@@ -1648,6 +1657,12 @@ ELF_File * elf_list_next(Context * ctx) {

 void elf_list_done(Context * ctx) {
     ElfListState * state = elf_list_state;
+    while (state->ctx != ctx)
+        state = state->next;
+
+    if (!state)
+        return;
+
     assert(state != NULL);
     assert(state->ctx == ctx);
     elf_list_state = state->next;