[ 3.5.y.z extended stable ] Patch "tty: set_termios/set_termiox should not return -EINTR" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    tty: set_termios/set_termiox should not return -EINTR

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From fc668b920679e347ed80d36da0b1b7c59677b672 Mon Sep 17 00:00:00 2001
From: Oleg Nesterov <oleg at redhat.com>
Date: Tue, 29 Jan 2013 20:07:41 +0100
Subject: [PATCH] tty: set_termios/set_termiox should not return -EINTR

commit 183d95cdd834381c594d3aa801c1f9f9c0c54fa9 upstream.

See https://bugzilla.redhat.com/show_bug.cgi?id=904907
read command causes bash to abort with double free or corruption (out).

A simple test-case from Roman:

	// Compile the reproducer and send sigchld ti that process.
	// EINTR occurs even if SA_RESTART flag is set.

	void handler(int sig)
	{
	}

	main()
	{
	  struct sigaction act;
	  act.sa_handler = handler;
	  act.sa_flags = SA_RESTART;
	  sigaction (SIGCHLD, &act, 0);
	  struct termio ttp;
	  ioctl(0, TCGETA, &ttp);
	  while(1)
	  {
	    if (ioctl(0, TCSETAW, ttp) < 0)
	      {
		if (errno == EINTR)
		{
		  fprintf(stderr, "BUG!"); return(1);
		}
	      }
	  }
	}

Change set_termios/set_termiox to return -ERESTARTSYS to fix this
particular problem.

I didn't dare to change other EINTR's in drivers/tty/, but they look
equally wrong.

Reported-by: Roman Rakus <rrakus at redhat.com>
Reported-by: Lingzhu Xiang <lxiang at redhat.com>
Signed-off-by: Oleg Nesterov <oleg at redhat.com>
Cc: Jiri Slaby <jslaby at suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/tty/tty_ioctl.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/tty_ioctl.c b/drivers/tty/tty_ioctl.c
index a1b9a2f..f8d03da 100644
--- a/drivers/tty/tty_ioctl.c
+++ b/drivers/tty/tty_ioctl.c
@@ -617,7 +617,7 @@ static int set_termios(struct tty_struct *tty, void __user *arg, int opt)
 	if (opt & TERMIOS_WAIT) {
 		tty_wait_until_sent(tty, 0);
 		if (signal_pending(current))
-			return -EINTR;
+			return -ERESTARTSYS;
 	}

 	tty_set_termios(tty, &tmp_termios);
@@ -684,7 +684,7 @@ static int set_termiox(struct tty_struct *tty, void __user *arg, int opt)
 	if (opt & TERMIOS_WAIT) {
 		tty_wait_until_sent(tty, 0);
 		if (signal_pending(current))
-			return -EINTR;
+			return -ERESTARTSYS;
 	}

 	mutex_lock(&tty->termios_mutex);
--
1.8.1.2