[PATCH v4 1/1] msvcrt: Don't release io memory in msvcrt_free_io during shutdown.

[Yuxuan Shui]

From: Yuxuan Shui

In kernel32/tests/loader.c, child_process will try to write to stdout after
calling LdrShutdownProcess. LdrShutdownProcess calls DLL_PROCESS_DETACH on
msvcrt, which calls msvcrt_free_io, which frees the ioinfo blocks. So to
prevent use after free in this case, we don't free them during shutdown.
---
 dlls/msvcrt/file.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/dlls/msvcrt/file.c b/dlls/msvcrt/file.c
index 97bfc746abc..e6bcf04d1ee 100644
--- a/dlls/msvcrt/file.c
+++ b/dlls/msvcrt/file.c
@@ -1395,6 +1395,11 @@ void msvcrt_free_io(void)
     int j;

_flushall();
+
+    /* Make sure stdio is still usable during shutdown. */
+    if (RtlDllShutdownInProgress())
+        return;
+
     _fcloseall();

for(i=0; i<ARRAY_SIZE(MSVCRT___pioinfo); i++)