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authorTakashi Yano <takashi.yano@nifty.ne.jp>2024-03-01 19:05:36 +0900
committerTakashi Yano <takashi.yano@nifty.ne.jp>2024-03-01 20:00:11 +0900
commitc77a5689f7bd4520f6d87481fd08591747b5da0f (patch)
treefd7c70113259f13593fe04a97f59a5555385877e /winsup/cygwin
parentee97ae1d5f4d42d47d828a1b4d9b05ec9cbfe042 (diff)
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Cygwin: console: Do not unmap shared console memory belonging to ctty.
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: 3721a756b0d8 ("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>
Diffstat (limited to 'winsup/cygwin')
-rw-r--r--winsup/cygwin/fhandler/console.cc8
-rw-r--r--winsup/cygwin/release/3.5.27
2 files changed, 12 insertions, 3 deletions
diff --git a/winsup/cygwin/fhandler/console.cc b/winsup/cygwin/fhandler/console.cc
index c16ca39..67ea954 100644
--- a/winsup/cygwin/fhandler/console.cc
+++ b/winsup/cygwin/fhandler/console.cc
@@ -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;
}
diff --git a/winsup/cygwin/release/3.5.2 b/winsup/cygwin/release/3.5.2
new file mode 100644
index 0000000..7d8df94
--- /dev/null
+++ b/winsup/cygwin/release/3.5.2
@@ -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