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sockfilt: fix race-condition of waiting threads and event handling

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Fix race-condition of waiting threads finishing while events are
already being processed which lead to invalid or skipped events.

Use mutex to check for one event at a time or do post-processing.
In addition to mutex-based locking use specific event as signal.

Closes #5156
This commit is contained in:
Marc Hoersken 2020-04-02 18:41:11 +02:00
parent 4506607b44
commit 9657ecb15b
No known key found for this signature in database
GPG Key ID: 61E03CBED7BC859E
1 changed files with 163 additions and 83 deletions
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136
tests/server/sockfilt.c
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@ -532,12 +532,14 @@ static void lograw(unsigned char *buffer, ssize_t len)
*/
struct select_ws_wait_data {
HANDLE handle; /* actual handle to wait for during select */
HANDLE event; /* internal event to abort waiting thread */
HANDLE signal; /* internal event to signal handle trigger */
HANDLE abort; /* internal event to abort waiting thread */
HANDLE mutex; /* mutex to prevent event race-condition */
};
static DWORD WINAPI select_ws_wait_thread(LPVOID lpParameter)
{
struct select_ws_wait_data *data;
HANDLE handle, handles[2];
HANDLE mutex, signal, handle, handles[2];
INPUT_RECORD inputrecord;
LARGE_INTEGER size, pos;
DWORD type, length;
@ -546,8 +548,10 @@ static DWORD WINAPI select_ws_wait_thread(LPVOID lpParameter)
data = (struct select_ws_wait_data *) lpParameter;
if(data) {
handle = data->handle;
handles[0] = data->event;
handles[0] = data->abort;
handles[1] = handle;
signal = data->signal;
mutex = data->mutex;
free(data);
}
else
@ -567,6 +571,8 @@ static DWORD WINAPI select_ws_wait_thread(LPVOID lpParameter)
*/
while(WaitForMultipleObjectsEx(1, handles, FALSE, 0, FALSE)
== WAIT_TIMEOUT) {
length = WaitForSingleObjectEx(mutex, 0, FALSE);
if(length == WAIT_OBJECT_0) {
/* get total size of file */
length = 0;
size.QuadPart = 0;
@ -584,14 +590,23 @@ static DWORD WINAPI select_ws_wait_thread(LPVOID lpParameter)
if(size.QuadPart == pos.QuadPart) {
/* sleep and continue waiting */
SleepEx(0, FALSE);
ReleaseMutex(mutex);
continue;
}
}
}
/* there is some data available, stop waiting */
logmsg("[select_ws_wait_thread] data available on DISK: %p", handle);
logmsg("[select_ws_wait_thread] data available, DISK: %p", handle);
SetEvent(signal);
ReleaseMutex(mutex);
break;
}
else if(length == WAIT_ABANDONED) {
/* we are not allowed to process this event, because select_ws
is post-processing the signalled events and we must exit. */
break;
}
}
break;
case FILE_TYPE_CHAR:
@ -604,6 +619,8 @@ static DWORD WINAPI select_ws_wait_thread(LPVOID lpParameter)
*/
while(WaitForMultipleObjectsEx(2, handles, FALSE, INFINITE, FALSE)
== WAIT_OBJECT_0 + 1) {
length = WaitForSingleObjectEx(mutex, 0, FALSE);
if(length == WAIT_OBJECT_0) {
/* check if this is an actual console handle */
length = 0;
if(GetConsoleMode(handle, &length)) {
@ -614,14 +631,23 @@ static DWORD WINAPI select_ws_wait_thread(LPVOID lpParameter)
if(length == 1 && inputrecord.EventType != KEY_EVENT) {
/* purge the non-key-event and continue waiting */
ReadConsoleInput(handle, &inputrecord, 1, &length);
ReleaseMutex(mutex);
continue;
}
}
}
/* there is some data available, stop waiting */
logmsg("[select_ws_wait_thread] data available on CHAR: %p", handle);
logmsg("[select_ws_wait_thread] data available, CHAR: %p", handle);
SetEvent(signal);
ReleaseMutex(mutex);
break;
}
else if(length == WAIT_ABANDONED) {
/* we are not allowed to process this event, because select_ws
is post-processing the signalled events and we must exit. */
break;
}
}
break;
case FILE_TYPE_PIPE:
@ -634,12 +660,15 @@ static DWORD WINAPI select_ws_wait_thread(LPVOID lpParameter)
*/
while(WaitForMultipleObjectsEx(1, handles, FALSE, 0, FALSE)
== WAIT_TIMEOUT) {
length = WaitForSingleObjectEx(mutex, 0, FALSE);
if(length == WAIT_OBJECT_0) {
/* peek into the pipe and retrieve the amount of data available */
length = 0;
if(PeekNamedPipe(handle, NULL, 0, NULL, &length, NULL)) {
/* if there is no data available, sleep and continue waiting */
if(length == 0) {
SleepEx(0, FALSE);
ReleaseMutex(mutex);
continue;
}
else {
@ -652,25 +681,41 @@ static DWORD WINAPI select_ws_wait_thread(LPVOID lpParameter)
logmsg("[select_ws_wait_thread] PeekNamedPipe error: %d", length);
if(length == ERROR_BROKEN_PIPE) {
SleepEx(0, FALSE);
ReleaseMutex(mutex);
continue;
}
}
/* there is some data available, stop waiting */
logmsg("[select_ws_wait_thread] data available on PIPE: %p", handle);
logmsg("[select_ws_wait_thread] data available, PIPE: %p", handle);
SetEvent(signal);
ReleaseMutex(mutex);
break;
}
else if(length == WAIT_ABANDONED) {
/* we are not allowed to process this event, because select_ws
is post-processing the signalled events and we must exit. */
break;
}
}
break;
default:
/* The handle has an unknown type, try to wait on it */
WaitForMultipleObjectsEx(2, handles, FALSE, INFINITE, FALSE);
logmsg("[select_ws_wait_thread] data available on HANDLE: %p", handle);
if(WaitForMultipleObjectsEx(2, handles, FALSE, INFINITE, FALSE)
== WAIT_OBJECT_0 + 1) {
if(WaitForSingleObjectEx(mutex, 0, FALSE) == WAIT_OBJECT_0) {
logmsg("[select_ws_wait_thread] data available, HANDLE: %p", handle);
SetEvent(signal);
ReleaseMutex(mutex);
}
}
break;
}
return 0;
}
static HANDLE select_ws_wait(HANDLE handle, HANDLE event)
static HANDLE select_ws_wait(HANDLE handle, HANDLE signal,
HANDLE abort, HANDLE mutex)
{
struct select_ws_wait_data *data;
HANDLE thread = NULL;
@ -679,7 +724,9 @@ static HANDLE select_ws_wait(HANDLE handle, HANDLE event)
data = malloc(sizeof(struct select_ws_wait_data));
if(data) {
data->handle = handle;
data->event = event;
data->signal = signal;
data->abort = abort;
data->mutex = mutex;
/* launch waiting thread */
thread = CreateThread(NULL, 0,
@ -695,21 +742,21 @@ static HANDLE select_ws_wait(HANDLE handle, HANDLE event)
return thread;
}
struct select_ws_data {
curl_socket_t fd; /* the original input handle (indexed by fds) */
curl_socket_t fd; /* the original input handle (indexed by fds/idx) */
curl_socket_t wsasock; /* the internal socket handle (indexed by wsa) */
WSAEVENT wsaevent; /* the internal WINSOCK2 event (indexed by wsa) */
HANDLE thread; /* the internal threads handle (indexed by thd) */
WSAEVENT wsaevent; /* the internal WINSOCK event (indexed by wsa) */
HANDLE signal; /* the internal signal handle (indexed by thd) */
HANDLE thread; /* the internal thread handle (indexed by thd) */
};
static int select_ws(int nfds, fd_set *readfds, fd_set *writefds,
fd_set *exceptfds, struct timeval *timeout)
{
HANDLE abort, mutex, signal, handle, *handles;
DWORD milliseconds, wait, idx;
WSANETWORKEVENTS wsanetevents;
struct select_ws_data *data;
HANDLE handle, *handles;
WSAEVENT wsaevent;
int error, fds;
HANDLE waitevent = NULL;
DWORD nfd = 0, thd = 0, wsa = 0;
int ret = 0;
@ -725,9 +772,17 @@ static int select_ws(int nfds, fd_set *readfds, fd_set *writefds,
return 0;
}
/* create internal event to signal waiting threads */
waitevent = CreateEvent(NULL, TRUE, FALSE, NULL);
if(!waitevent) {
/* create internal event to abort waiting threads */
abort = CreateEvent(NULL, TRUE, FALSE, NULL);
if(!abort) {
errno = ENOMEM;
return -1;
}
/* create internal mutex to lock event handling in threads */
mutex = CreateMutex(NULL, FALSE, NULL);
if(!mutex) {
CloseHandle(abort);
errno = ENOMEM;
return -1;
}
@ -735,7 +790,8 @@ static int select_ws(int nfds, fd_set *readfds, fd_set *writefds,
/* allocate internal array for the internal data */
data = calloc(nfds, sizeof(struct select_ws_data));
if(data == NULL) {
CloseHandle(waitevent);
CloseHandle(abort);
CloseHandle(mutex);
errno = ENOMEM;
return -1;
}
@ -743,7 +799,8 @@ static int select_ws(int nfds, fd_set *readfds, fd_set *writefds,
/* allocate internal array for the internal event handles */
handles = calloc(nfds, sizeof(HANDLE));
if(handles == NULL) {
CloseHandle(waitevent);
CloseHandle(abort);
CloseHandle(mutex);
free(data);
errno = ENOMEM;
return -1;
@ -768,11 +825,20 @@ static int select_ws(int nfds, fd_set *readfds, fd_set *writefds,
data[nfd].fd = curlx_sitosk(fds);
if(fds == fileno(stdin)) {
handle = GetStdHandle(STD_INPUT_HANDLE);
handle = select_ws_wait(handle, waitevent);
handles[nfd] = handle;
signal = CreateEvent(NULL, TRUE, FALSE, NULL);
if(signal) {
handle = select_ws_wait(handle, signal, abort, mutex);
if(handle) {
handles[nfd] = signal;
data[thd].signal = signal;
data[thd].thread = handle;
thd++;
}
else {
CloseHandle(signal);
}
}
}
else if(fds == fileno(stdout)) {
handles[nfd] = GetStdHandle(STD_OUTPUT_HANDLE);
}
@ -794,11 +860,20 @@ static int select_ws(int nfds, fd_set *readfds, fd_set *writefds,
curl_socket_t socket = curlx_sitosk(fds);
WSACloseEvent(wsaevent);
handle = (HANDLE) socket;
handle = select_ws_wait(handle, waitevent);
handles[nfd] = handle;
signal = CreateEvent(NULL, TRUE, FALSE, NULL);
if(signal) {
handle = select_ws_wait(handle, signal, abort, mutex);
if(handle) {
handles[nfd] = signal;
data[thd].signal = signal;
data[thd].thread = handle;
thd++;
}
else {
CloseHandle(signal);
}
}
}
}
}
nfd++;
@ -816,8 +891,8 @@ static int select_ws(int nfds, fd_set *readfds, fd_set *writefds,
/* wait for one of the internal handles to trigger */
wait = WaitForMultipleObjectsEx(nfd, handles, FALSE, milliseconds, FALSE);
/* signal the event handle for the waiting threads */
SetEvent(waitevent);
/* wait for internal mutex to lock event handling in threads */
WaitForSingleObjectEx(mutex, INFINITE, FALSE);
/* loop over the internal handles returned in the descriptors */
for(idx = 0; idx < nfd; idx++) {
@ -881,6 +956,9 @@ static int select_ws(int nfds, fd_set *readfds, fd_set *writefds,
}
}
/* signal the event handle for the other waiting threads */
SetEvent(abort);
for(fds = 0; fds < nfds; fds++) {
if(FD_ISSET(fds, readfds))
logmsg("select_ws: %d is readable", fds);
@ -898,11 +976,13 @@ static int select_ws(int nfds, fd_set *readfds, fd_set *writefds,
}
for(idx = 0; idx < thd; idx++) {
WaitForSingleObject(data[idx].thread, INFINITE);
WaitForSingleObjectEx(data[idx].thread, INFINITE, FALSE);
CloseHandle(data[idx].thread);
CloseHandle(data[idx].signal);
}
CloseHandle(waitevent);
CloseHandle(abort);
CloseHandle(mutex);
free(handles);
free(data);