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author | Takashi Yano <takashi.yano@nifty.ne.jp> | 2022-01-14 19:35:12 +0900 |
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committer | Takashi Yano <takashi.yano@nifty.ne.jp> | 2022-01-14 23:11:20 +0900 |
commit | 909ed837ccb932ea70f71cc41891fa2c8143133f (patch) | |
tree | 1ec642af25b68216dd65b2516e0f4c00fbabcc93 | |
parent | bff4594b089c10c41edcdd14c2682d19f36b3241 (diff) | |
download | newlib-909ed837ccb932ea70f71cc41891fa2c8143133f.zip newlib-909ed837ccb932ea70f71cc41891fa2c8143133f.tar.gz newlib-909ed837ccb932ea70f71cc41891fa2c8143133f.tar.bz2 |
Cygwin: pty: Fix race issue between closing and opening master.
- If the from_master is closed before cleaning up other pipes, such
as from_slave_nat, the same pty may be allocated and pty master may
try to open the pipe which is not closed yet, and it will fail.
This patch fixes the issue.
-rw-r--r-- | winsup/cygwin/fhandler_tty.cc | 14 |
1 files changed, 10 insertions, 4 deletions
diff --git a/winsup/cygwin/fhandler_tty.cc b/winsup/cygwin/fhandler_tty.cc index 1ae4edd..7bef695 100644 --- a/winsup/cygwin/fhandler_tty.cc +++ b/winsup/cygwin/fhandler_tty.cc @@ -2146,8 +2146,6 @@ fhandler_pty_master::close () if (!ForceCloseHandle (from_master_nat)) termios_printf ("error closing from_master_nat %p, %E", from_master_nat); - if (!ForceCloseHandle (from_master)) - termios_printf ("error closing from_master %p, %E", from_master); if (!ForceCloseHandle (to_master_nat)) termios_printf ("error closing to_master_nat %p, %E", to_master_nat); from_master_nat = to_master_nat = NULL; @@ -2156,7 +2154,7 @@ fhandler_pty_master::close () from_slave_nat = NULL; if (!ForceCloseHandle (to_master)) termios_printf ("error closing to_master %p, %E", to_master); - to_master = from_master = NULL; + to_master = NULL; ForceCloseHandle (echo_r); ForceCloseHandle (echo_w); echo_r = echo_w = NULL; @@ -2171,6 +2169,12 @@ fhandler_pty_master::close () termios_printf ("CloseHandle (input_available_event<%p>), %E", input_available_event); + /* The from_master must be closed last so that the same pty is not + allocated before cleaning up the other corresponding instances. */ + if (!ForceCloseHandle (from_master)) + termios_printf ("error closing from_master %p, %E", from_master); + from_master = NULL; + return 0; } @@ -3069,12 +3073,14 @@ err: close_maybe (output_mutex); close_maybe (input_mutex); close_maybe (from_master_nat); - close_maybe (from_master); close_maybe (to_master_nat); close_maybe (to_master); close_maybe (echo_r); close_maybe (echo_w); close_maybe (master_ctl); + /* The from_master must be closed last so that the same pty is not + allocated before cleaning up the other corresponding instances. */ + close_maybe (from_master); termios_printf ("pty%d open failed - failed to create %s", unit, errstr); return false; } |