dbghelp: Fix vdso.so lookup.

dlls/dbghelp/dbghelp_private.h

@@ -523,6 +523,15 @@ static inline BOOL read_process_memory(const struct process *process, UINT64 add
     return ReadProcessMemory(process->handle, (void*)(UINT_PTR)addr, buf, size, NULL);
 }
 
+static inline BOOL read_process_integral_value(const struct process* process, UINT64 addr, UINT64* pvalue, size_t size)
+{
+    /* Assuming that debugger and debuggee are little endian. */
+    UINT64 value = 0;
+    if (size > sizeof(value) || !read_process_memory(process, addr, &value, size)) return FALSE;
+    *pvalue = value;
+    return TRUE;
+}
+
 struct line_info
 {
     ULONG_PTR                   is_first : 1,

dlls/dbghelp/elf_module.c

@@ -1339,39 +1339,51 @@ static BOOL elf_load_file_cb(void *param, HANDLE handle, const WCHAR *filename)
 /******************************************************************
  *		elf_search_auxv
  *
- * locate some a value from the debuggee auxiliary vector
+ * Locate a value from the debuggee auxiliary vector
  */
 static BOOL elf_search_auxv(const struct process* pcs, unsigned type, ULONG_PTR* val)
 {
     char        buffer[sizeof(SYMBOL_INFO) + MAX_SYM_NAME];
     SYMBOL_INFO*si = (SYMBOL_INFO*)buffer;
-    BYTE*       addr;
-    BYTE*       str;
-    BYTE*       str_max;
+    const unsigned ptr_size = pcs->is_system_64bit ? 8 : 4;
+    UINT64      envp;
+    UINT64      addr;
+    UINT64      str;
+    UINT64      str_max;
 
     si->SizeOfStruct = sizeof(*si);
     si->MaxNameLen = MAX_SYM_NAME;
-    if (!SymFromName(pcs->handle, "libwine.so.1!__wine_main_environ", si) ||
-        !(addr = (void*)(DWORD_PTR)si->Address) ||
-        !ReadProcessMemory(pcs->handle, addr, &addr, sizeof(addr), NULL) ||
-        !addr)
+    if (!SymFromName(pcs->handle, "ntdll.so!main_envp", si) ||
+        !si->Address ||
+        !read_process_integral_value(pcs, si->Address, &envp, ptr_size) ||
+        !envp)
     {
         FIXME("can't find symbol in module\n");
         return FALSE;
     }
     /* walk through envp[] */
     /* envp[] strings are located after the auxiliary vector, so protect the walk */
-    str_max = (void*)(DWORD_PTR)~0L;
-    while (ReadProcessMemory(pcs->handle, addr, &str, sizeof(str), NULL) &&
-           (addr = (void*)((DWORD_PTR)addr + sizeof(str))) != NULL && str != NULL)
-        str_max = min(str_max, str);
+    str_max = ~(UINT64)0u;
+    addr = envp;
+    for (;;)
+    {
+        if (!read_process_integral_value(pcs, addr, &str, ptr_size) || (addr += ptr_size) <= ptr_size)
+            return FALSE;
+        if (!str) break;
+        /* It can be some env vars have been changed, pointing to a different location */
+        if (str >= envp)
+            str_max = min(str_max, str);
+    }
 
     /* Walk through the end of envp[] array.
      * Actually, there can be several NULLs at the end of envp[]. This happens when an env variable is
      * deleted, the last entry is replaced by an extra NULL.
      */
-    while (addr < str_max && ReadProcessMemory(pcs->handle, addr, &str, sizeof(str), NULL) && str == NULL)
-        addr = (void*)((DWORD_PTR)addr + sizeof(str));
+    for (; addr < str_max; addr += ptr_size)
+    {
+        if (!read_process_integral_value(pcs, addr, &str, ptr_size)) return FALSE;
+        if (str) break;
+    }
 
     if (pcs->is_system_64bit)
     {
@@ -1381,7 +1393,7 @@ static BOOL elf_search_auxv(const struct process* pcs, unsigned type, ULONG_PTR*
             UINT64 a_val;
         } auxv;
 
-        while (ReadProcessMemory(pcs->handle, addr, &auxv, sizeof(auxv), NULL) && auxv.a_type)
+        while (read_process_memory(pcs, addr, &auxv, sizeof(auxv)) && auxv.a_type)
         {
             if (auxv.a_type == type)
             {
@@ -1399,7 +1411,7 @@ static BOOL elf_search_auxv(const struct process* pcs, unsigned type, ULONG_PTR*
             UINT32 a_val;
         } auxv;
 
-        while (ReadProcessMemory(pcs->handle, addr, &auxv, sizeof(auxv), NULL) && auxv.a_type)
+        while (read_process_memory(pcs, addr, &auxv, sizeof(auxv)) && auxv.a_type)
         {
             if (auxv.a_type == type)
             {