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Cygwin: console: Do not unmap shared console memory belonging to ctty.

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In the condition that console setup for CTTY and close run at the
sametime, accessing shared console memory which is already unmapped
may occur. With this patch, to avoid this race issue, shared console
memory which belongs to contorolling terminal (CTTY) is kept mapped
as before.
Addresses: https://cygwin.com/pipermail/cygwin/2024-February/255561.html

Fixes: 3721a756b0 ("Cygwin: console: Make the console accessible from other terminals.")
Reported-by: Kate Deplaix <kit-ty-kate@outlook.com>
Signed-off-by: Takashi Yano <takashi.yano@nifty.ne.jp>
This commit is contained in:
Takashi Yano 2024-03-01 19:05:36 +09:00
parent ee97ae1d5f
commit c77a5689f7
2 changed files with 12 additions and 3 deletions
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8
winsup/cygwin/fhandler/console.cc
View file

@ -1926,9 +1926,11 @@ fhandler_console::close ()
|| get_device () == (dev_t) myself->ctty))
free_console ();
if (shared_console_info[unit])
UnmapViewOfFile ((void *) shared_console_info[unit]);
shared_console_info[unit] = NULL;
if (shared_console_info[unit] && myself->ctty != tc ()->ntty)
{
UnmapViewOfFile ((void *) shared_console_info[unit]);
shared_console_info[unit] = NULL;
}
return 0;
}

7
winsup/cygwin/release/3.5.2 Normal file
View file

@ -0,0 +1,7 @@
Fixes:
------
- Fix the problem that console setup accesses shared memory which
is already unmapped due to race condition. To avoid this issue,
shared console memory will be kept mapped if it belongs to CTTY.
Addresses: https://cygwin.com/pipermail/cygwin/2024-February/255561.html