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Cygwin: console: Fix potential deadlock regarding acuqiring mutex. 

- Acquiring input_mutex and attach_mutex in console code has potential
  risk of deadlock. This patch fixes the issue.
This commit is contained in:
Takashi Yano 2022-01-13 20:57:15 +09:00
parent 3af461092e
commit bff4594b08
2 changed files with 6 additions and 3 deletions
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2
winsup/cygwin/fhandler.h
View File

@ -2208,9 +2208,11 @@ private:
void acquire_input_mutex_if_necessary (DWORD ms) void acquire_input_mutex_if_necessary (DWORD ms)
{ {
acquire_input_mutex (ms); acquire_input_mutex (ms);
acquire_attach_mutex (ms);
} }
void release_input_mutex_if_necessary (void) void release_input_mutex_if_necessary (void)
{ {
release_attach_mutex ();
release_input_mutex (); release_input_mutex ();
} }

7
winsup/cygwin/select.cc
View File

@ -1122,29 +1122,30 @@ peek_console (select_record *me, bool)
HANDLE h; HANDLE h;
set_handle_or_return_if_not_open (h, me); set_handle_or_return_if_not_open (h, me);
fh->acquire_input_mutex (mutex_timeout);
acquire_attach_mutex (mutex_timeout); acquire_attach_mutex (mutex_timeout);
while (!fh->input_ready && !fh->get_cons_readahead_valid ()) while (!fh->input_ready && !fh->get_cons_readahead_valid ())
{ {
if (fh->bg_check (SIGTTIN, true) <= bg_eof) if (fh->bg_check (SIGTTIN, true) <= bg_eof)
{ {
release_attach_mutex (); release_attach_mutex ();
fh->release_input_mutex ();
return me->read_ready = true; return me->read_ready = true;
} }
else if (!PeekConsoleInputW (h, &irec, 1, &events_read) || !events_read) else if (!PeekConsoleInputW (h, &irec, 1, &events_read) || !events_read)
break; break;
fh->acquire_input_mutex (mutex_timeout);
if (fhandler_console::input_winch == fh->process_input_message () if (fhandler_console::input_winch == fh->process_input_message ()
&& global_sigs[SIGWINCH].sa_handler != SIG_IGN && global_sigs[SIGWINCH].sa_handler != SIG_IGN
&& global_sigs[SIGWINCH].sa_handler != SIG_DFL) && global_sigs[SIGWINCH].sa_handler != SIG_DFL)
{ {
set_sig_errno (EINTR); set_sig_errno (EINTR);
fh->release_input_mutex ();
release_attach_mutex (); release_attach_mutex ();
fh->release_input_mutex ();
return -1; return -1;
} }
fh->release_input_mutex ();
} }
release_attach_mutex (); release_attach_mutex ();
fh->release_input_mutex ();
if (fh->input_ready || fh->get_cons_readahead_valid ()) if (fh->input_ready || fh->get_cons_readahead_valid ())
return me->read_ready = true; return me->read_ready = true;