[PATCH 1/1] ntdll/tests: Check if writing to fs and gs causes child processes to crash.

[Bernhard Übelacker]

From: Bernhard Übelacker

Similar to 4e4847dd71 which disabled writes to fs and gs register in
"cleared segment registers" test: https://bugs.winehq.org/show_bug.cgi?id=51152

Followup to 03fe2b36cd.
---
 dlls/ntdll/tests/exception.c | 49 ++++++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)

diff --git a/dlls/ntdll/tests/exception.c b/dlls/ntdll/tests/exception.c
index 025923b7d8e..7da6d3a1cf0 100644
--- a/dlls/ntdll/tests/exception.c
+++ b/dlls/ntdll/tests/exception.c
@@ -9453,6 +9453,12 @@ static void test_debuggee_segments(void)
 {
     void (CDECL *func)(void) = code_mem;

+    if (GetEnvironmentVariableA("AVOID_FS_GS_WRITE", NULL, 0))
+    {
+        skip("Processes modifying fs/gs registers are crashing, skipping test.\n");
+        return;
+    }
+
     memcpy( code_mem, except_code_segments, sizeof(except_code_segments));
     func();
 }
@@ -12068,6 +12074,42 @@ static void test_context_exception_request(void)
     CloseHandle( p.event );
 }

+static void fs_gs_write(void)
+{
+    __asm__(
+        "mov %fs,%eax; "
+        "mov %eax,%fs; "
+        "mov %gs,%eax; "
+        "mov %eax,%gs"
+    );
+    trace("Wrote to fs and gs registers.\n");
+}
+
+static void fs_gs_write_check(void)
+{
+    char **argv;
+    char cmdline[MAX_PATH];
+    STARTUPINFOA si = {.cb = sizeof(si)};
+    PROCESS_INFORMATION pi;
+    DWORD ret;
+
+    if (!winetest_platform_is_wine)
+        return;
+
+    winetest_get_mainargs(&argv);
+    sprintf(cmdline, "%s exception fs_gs_write", argv[0]);
+    ret = CreateProcessA(NULL, cmdline, NULL, NULL, TRUE, 0, NULL, NULL, &si, &pi);
+    ok(ret, "Failed to create target process.\n");
+
+    WaitForSingleObject(pi.hProcess, 30000);
+    ok(GetExitCodeProcess(pi.hProcess, &ret), "GetExitCodeProcess failed.\n");
+    if (ret)
+        SetEnvironmentVariableA("AVOID_FS_GS_WRITE", "1");
+
+    CloseHandle(pi.hProcess);
+    CloseHandle(pi.hThread);
+}
+
 START_TEST(exception)
 {
     HMODULE hkernel32 = GetModuleHandleA("kernel32.dll");
@@ -12081,6 +12123,12 @@ START_TEST(exception)
         return;
     }

+    if (my_argc >= 3 && !strcmp(my_argv[2], "fs_gs_write"))
+    {
+        fs_gs_write();
+        return;
+    }
+
     code_mem = VirtualAlloc(NULL, 65536, MEM_RESERVE | MEM_COMMIT, PAGE_EXECUTE_READWRITE);
     if(!code_mem) {
         trace("VirtualAlloc failed\n");
@@ -12333,6 +12381,7 @@ START_TEST(exception)
     test_KiUserApcDispatcher();
     test_KiUserCallbackDispatcher();
     test_rtlraiseexception();
+    fs_gs_write_check();
     test_debugger(DBG_EXCEPTION_HANDLED, FALSE);
     test_debugger(DBG_CONTINUE, FALSE);
     test_debugger(DBG_EXCEPTION_HANDLED, TRUE);