diff options
Diffstat (limited to 'winsup/cygwin/fhandler/process.cc')
| -rw-r--r-- | winsup/cygwin/fhandler/process.cc | 33 |
1 files changed, 30 insertions, 3 deletions
diff --git a/winsup/cygwin/fhandler/process.cc b/winsup/cygwin/fhandler/process.cc index 8fae9be..e00cae5 100644 --- a/winsup/cygwin/fhandler/process.cc +++ b/winsup/cygwin/fhandler/process.cc @@ -621,14 +621,39 @@ struct heap_info : heap_vm_chunks (NULL) { PDEBUG_BUFFER buf; + wchar_t mtx_name [32]; + HANDLE mtx; NTSTATUS status; PDEBUG_HEAP_ARRAY harray; + /* We need a global mutex here, because RtlQueryProcessDebugInformation + is neither thread-safe, nor multi-process-safe. If it's called in + parallel on the same process it can crash that process. We can't + avoid this if a non-Cygwin app calls RtlQueryProcessDebugInformation + on the same process in parallel, but we can avoid Cygwin processes + crashing process PID just because they open /proc/PID/maps in parallel + by serializing RtlQueryProcessDebugInformation on the same process. + + Note that the mutex guards the entire code from + RtlCreateQueryDebugBuffer to RtlDestroyQueryDebugBuffer including the + code accessing the debug buffer. Apparently the debug buffer needs + safeguarded against parallel access all the time it's used!!! */ + __small_swprintf (mtx_name, L"cyg-heapinfo-mtx-%u", pid); + mtx = CreateMutexW (&sec_none_nih, FALSE, mtx_name); + if (!mtx) + return; + WaitForSingleObject (mtx, INFINITE); buf = RtlCreateQueryDebugBuffer (16 * 65536, FALSE); + if (buf) + status = RtlQueryProcessDebugInformation (pid, + PDI_HEAPS | PDI_HEAP_BLOCKS, + buf); if (!buf) - return; - status = RtlQueryProcessDebugInformation (pid, PDI_HEAPS | PDI_HEAP_BLOCKS, - buf); + { + ReleaseMutex (mtx); + CloseHandle (mtx); + return; + } if (NT_SUCCESS (status) && (harray = (PDEBUG_HEAP_ARRAY) buf->HeapInformation) != NULL) for (ULONG hcnt = 0; hcnt < harray->Count; ++hcnt) @@ -653,6 +678,8 @@ struct heap_info } } RtlDestroyQueryDebugBuffer (buf); + ReleaseMutex (mtx); + CloseHandle (mtx); } char *fill_if_match (char *base, ULONG type, char *dest) |