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Cygwin: console: Fix segfault on shared_console_info access.

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- Accessing shared_console_info before initialization causes access
  violation because it is a NULL pointer. The cause of the problem
  reported in https://cygwin.com/ml/cygwin/2020-02/msg00197.html is
  this NULL pointer access in request_xterm_mode_output() when it is
  called from close(). This patch makes sure that shared_console_info
  is not NULL before calling request_xterm_mode_output().
This commit is contained in:
Takashi Yano 2020-02-25 01:12:16 +09:00 committed by Corinna Vinschen
parent 86f9ce97bc
commit 17528b9d2c
2 changed files with 15 additions and 12 deletions
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23
winsup/cygwin/fhandler_console.cc
View File

@ -1159,18 +1159,17 @@ fhandler_console::close ()
acquire_output_mutex (INFINITE);
if (shared_console_info && myself->pid == con.owner &&
wincap.has_con_24bit_colors () && !con_is_legacy)
request_xterm_mode_output (false);
/* Restore console mode if this is the last closure. */
OBJECT_BASIC_INFORMATION obi;
NTSTATUS status;
status = NtQueryObject (get_handle (), ObjectBasicInformation,
&obi, sizeof obi, NULL);
if (NT_SUCCESS (status) && obi.HandleCount == 1)
if (wincap.has_con_24bit_colors ())
request_xterm_mode_output (false);
if (shared_console_info && wincap.has_con_24bit_colors ())
{
/* Restore console mode if this is the last closure. */
OBJECT_BASIC_INFORMATION obi;
NTSTATUS status;
status = NtQueryObject (get_handle (), ObjectBasicInformation,
&obi, sizeof obi, NULL);
if ((NT_SUCCESS (status) && obi.HandleCount == 1)
|| myself->pid == con.owner)
request_xterm_mode_output (false);
}
release_output_mutex ();

4
winsup/cygwin/release/3.1.5
View File

@ -5,3 +5,7 @@ Bug Fixes:
Don't move cursor to the right in case of a NUL character in the console
output stream, this is not backed by terminfo.
Addresses: https://cygwin.com/ml/cygwin/2020-02/msg00162.html
- Fix a segfault when starting, e.g., mintty from a bash in a console
running xterm emulation.
Addresses: https://cygwin.com/ml/cygwin/2020-02/msg00197.html