From owner-freebsd-hackers Sun Feb 17 13:52:44 2002 Delivered-To: freebsd-hackers@freebsd.org Received: from web14205.mail.yahoo.com (web14205.mail.yahoo.com [216.136.172.151]) by hub.freebsd.org (Postfix) with SMTP id B001337B400 for ; Sun, 17 Feb 2002 13:52:40 -0800 (PST) Message-ID: <20020217215240.6584.qmail@web14205.mail.yahoo.com> Received: from [12.44.190.11] by web14205.mail.yahoo.com via HTTP; Sun, 17 Feb 2002 13:52:40 PST Date: Sun, 17 Feb 2002 13:52:40 -0800 (PST) From: Neelkanth Natu Subject: bug in ptcwrite() To: freebsd-hackers@freebsd.org MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG Hi, The following code in ptcwrite() in kern/tty_pty.c is supposed to prevent the tty input buffer overflow (for certain cases): 612 if ((tp->t_rawq.c_cc + tp->t_canq.c_cc) >= TTYHOG - 2 && 613 (tp->t_canq.c_cc > 0 || !(tp->t_iflag&ICANON))) { 614 wakeup(TSA_HUP_OR_INPUT(tp)); 615 goto block; 616 } But the ICANON flag is set in tp->t_lflag and not tp->t_iflag. The ICRNL flag in tp->t_iflag has the same value as the ICANON flag in tp->t_lflag (0x100). This leads to input buffer overflow as soon as the ICRNL bit is set in tp->t_iflag, and there are more than 1024 characters that telnet/ssh wants to write to the pty. I discovered this problem when using libreadline because it changes the terminal settings every time it is begins/finishes reading a line. Has anyone else seen a similar problem ? I saw identical behavior on NetBSD too. Please CC me as I am not on the mailing list. thanks Neel __________________________________________________ Do You Yahoo!? Yahoo! Sports - Coverage of the 2002 Olympic Games http://sports.yahoo.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message