[PATCH v2 0/1] MR7870: kernelbase: fix racing condition in GlobalMemoryStatusEx()

[Rastislav Stanik (＠rastos)]

use a critical section to guard access to local static variable with cached information

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=58082

--
  v2: kernelbase: fix racing condition in GlobalMemoryStatusEx()
 
https://gitlab.winehq.org/wine/wine/-/merge_requests/7870

[PATCH v2 1/1] kernelbase: fix racing condition in GlobalMemoryStatusEx()

[Rastislav Stanik]

From: Rastislav Stanik <git(a)rastos.org>

use a critical section to guard access to local static variable with cached information

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=58082
---
 dlls/kernelbase/memory.c | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/dlls/kernelbase/memory.c b/dlls/kernelbase/memory.c
index 0be178f6ab7..84968c0f386 100644
--- a/dlls/kernelbase/memory.c
+++ b/dlls/kernelbase/memory.c
@@ -42,6 +42,14 @@ WINE_DECLARE_DEBUG_CHANNEL(virtual);
 WINE_DECLARE_DEBUG_CHANNEL(globalmem);
 
 
+static CRITICAL_SECTION memstatus_section;
+static CRITICAL_SECTION_DEBUG critsect_debug =
+{
+    0, 0, &memstatus_section,
+    { &critsect_debug.ProcessLocksList, &critsect_debug.ProcessLocksList },
+      0, 0, { (DWORD_PTR)(__FILE__ ": memstatus_section") }
+};
+static CRITICAL_SECTION memstatus_section = { &critsect_debug, -1, 0, 0, 0, 0 };
 
 static CROSS_PROCESS_WORK_LIST *open_cross_process_connection( HANDLE process )
 {
@@ -1343,12 +1351,13 @@ BOOL WINAPI DECLSPEC_HOTPATCH GlobalMemoryStatusEx( MEMORYSTATUSEX *status )
         SetLastError( ERROR_INVALID_PARAMETER );
         return FALSE;
     }
-    if ((NtGetTickCount() - last_check) < 1000)
+    RtlEnterCriticalSection(&memstatus_section);
+    if ((NtGetTickCount() - last_check) < 1000 && cached_status.dwLength > 0)
     {
 	*status = cached_status;
+	RtlLeaveCriticalSection(&memstatus_section);
 	return TRUE;
     }
-    last_check = NtGetTickCount();
 
     if (!set_ntstatus( NtQuerySystemInformation( SystemBasicInformation,
                                                  &basic_info, sizeof(basic_info), NULL )) ||
@@ -1356,7 +1365,10 @@ BOOL WINAPI DECLSPEC_HOTPATCH GlobalMemoryStatusEx( MEMORYSTATUSEX *status )
                                                  &perf_info, sizeof(perf_info), NULL)) ||
         !set_ntstatus( NtQueryInformationProcess( GetCurrentProcess(), ProcessVmCounters,
                                                   &vmc, sizeof(vmc), NULL )))
+    {
+        RtlLeaveCriticalSection(&memstatus_section);
         return FALSE;
+    }
 
     status->dwMemoryLoad     = 0;
     status->ullTotalPhys     = basic_info.MmNumberOfPhysicalPages;
@@ -1381,6 +1393,8 @@ BOOL WINAPI DECLSPEC_HOTPATCH GlobalMemoryStatusEx( MEMORYSTATUSEX *status )
                      status->ullAvailPageFile, status->ullTotalVirtual, status->ullAvailVirtual );
 
     cached_status = *status;
+    last_check = NtGetTickCount();
+    RtlLeaveCriticalSection(&memstatus_section);
     return TRUE;
 }
 
-- 
GitLab

https://gitlab.winehq.org/wine/wine/-/merge_requests/7870