From: Takashi Yano <takashi.yano@nifty.ne.jp>
To: cygwin-patches@cygwin.com
Cc: Takashi Yano <takashi.yano@nifty.ne.jp>,
Bruce Jerrick <bmj001@gmail.com>
Subject: [PATCH 1/2] Cygwin: stat(): Fix "Bad address" error on stat() for /dev/tty.
Date: Fri, 7 Jul 2023 12:34:57 +0900 [thread overview]
Message-ID: <20230707033458.1034-2-takashi.yano@nifty.ne.jp> (raw)
In-Reply-To: <20230707033458.1034-1-takashi.yano@nifty.ne.jp>
As reported in
https://cygwin.com/pipermail/cygwin/2023-June/253888.html,
"Bad address" error occurs when stat() is called after the commit
3721a756b0d8 ("Cygwin: console: Make the console accessible from
other terminals.").
There are two problems in the current code. One is fhandler_console::
fstat() calls get_ttyp()->getsid(). However, fh_alloc() in dtable.cc
omits to initialize the fhandler_console instance when stat() is
called. Due to this, get_ttyp() returns NULL and access violation
occurs. The other problem is fh_alloc() assigns fhandler_console
even if the CTTY is not a console. So the first problem above occurs
even if the CTTY is a pty.
This patch fixes the issue by:
1) Call set_unit() to initialize _tc if the get_ttyp() returns NULL.
2) Assign fhandler_pty_slave for /dev/tty if CTTY is a pty in fh_alloc().
Fixes: 3721a756b0d8 ("Cygwin: console: Make the console accessible
from other terminals.").
Fixes: 23771fa1f7028 ("dtable.cc (fh_alloc): Make different decisions
when generating fhandler for not-opened devices. Add kludge to deal
with opening /dev/tty.")
Reported-by: Bruce Jerrick <bmj001@gmail.com>
Signed-off-by: Takashi Yano <takashi.yano@nifty.ne.jp>
---
winsup/cygwin/dtable.cc | 8 +++++++-
winsup/cygwin/fhandler/console.cc | 6 ++++++
2 files changed, 13 insertions(+), 1 deletion(-)
diff --git a/winsup/cygwin/dtable.cc b/winsup/cygwin/dtable.cc
index 18e0f3097..2aae2fd65 100644
--- a/winsup/cygwin/dtable.cc
+++ b/winsup/cygwin/dtable.cc
@@ -600,7 +600,13 @@ fh_alloc (path_conv& pc)
case FH_TTY:
if (!pc.isopen ())
{
- fhraw = cnew_no_ctor (fhandler_console, -1);
+ if (CTTY_IS_VALID (myself->ctty))
+ {
+ if (iscons_dev (myself->ctty))
+ fhraw = cnew_no_ctor (fhandler_console, -1);
+ else
+ fhraw = cnew_no_ctor (fhandler_pty_slave, -1);
+ }
debug_printf ("not called from open for /dev/tty");
}
else if (!CTTY_IS_VALID (myself->ctty) && last_tty_dev
diff --git a/winsup/cygwin/fhandler/console.cc b/winsup/cygwin/fhandler/console.cc
index 7768a9941..6aa3b50bf 100644
--- a/winsup/cygwin/fhandler/console.cc
+++ b/winsup/cygwin/fhandler/console.cc
@@ -4554,6 +4554,12 @@ fhandler_console::set_disable_master_thread (bool x, fhandler_console *cons)
int
fhandler_console::fstat (struct stat *st)
{
+ /* When stat() is called, fh_alloc() in dtable.cc omits to initialize
+ the console instance. Due to this, get_ttyp() returns NULL here.
+ So, calling set_unit() is necessary to access getsid(). */
+ if (!get_ttyp ())
+ set_unit ();
+
fhandler_base::fstat (st);
st->st_mode = S_IFCHR | S_IRUSR | S_IWUSR;
pinfo p (get_ttyp ()->getsid ());
--
2.39.0
next prev parent reply other threads:[~2023-07-07 3:35 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-07 3:34 [PATCH 0/2] Fix issues of stat()/fstat() " Takashi Yano
2023-07-07 3:34 ` Takashi Yano [this message]
2023-07-07 9:46 ` [PATCH 1/2] Cygwin: stat(): Fix "Bad address" error on stat() " Corinna Vinschen
2023-07-07 22:59 ` Takashi Yano
2023-07-10 8:31 ` Corinna Vinschen
2023-07-07 3:34 ` [PATCH 2/2] Cygwin: fstat(): Fix st_rdev returned by fstat() " Takashi Yano
2023-07-07 10:10 ` Corinna Vinschen
2023-07-07 23:01 ` Takashi Yano
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