Commit 19e2ad6a authored by Peter Hurley's avatar Peter Hurley Committed by Greg Kroah-Hartman
Browse files

n_tty: Remove overflow tests from receive_buf() path 



Always pre-figure the space available in the read_buf and limit
the inbound receive request to that amount.

For compatibility reasons with the non-flow-controlled interface,
n_tty_receive_buf() will continue filling read_buf until all data
has been received or receive_room() returns 0.

Signed-off-by: default avatarPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 7de971b0

drivers/tty/n_tty.c

+37 −48
Original line number Diff line number Diff line
@@ -316,12 +316,9 @@ static inline void n_tty_check_unthrottle(struct tty_struct *tty) 
 *	not active.

 */



static void put_tty_queue(unsigned char c, struct n_tty_data *ldata)

static inline void put_tty_queue(unsigned char c, struct n_tty_data *ldata)

{

	if (read_cnt(ldata) < N_TTY_BUF_SIZE) {

		*read_buf_addr(ldata, ldata->read_head) = c;

		ldata->read_head++;

	}

	*read_buf_addr(ldata, ldata->read_head++) = c;

}



/**
@@ -1333,11 +1330,6 @@ n_tty_receive_char_special(struct tty_struct *tty, unsigned char c) 
			return;

		}

		if (c == '\n') {

			if (read_cnt(ldata) >= N_TTY_BUF_SIZE) {

				if (L_ECHO(tty))

					process_output('\a', tty);

				return;

			}

			if (L_ECHO(tty) || L_ECHONL(tty)) {

				echo_char_raw('\n', ldata);

				commit_echoes(tty);
@@ -1345,8 +1337,6 @@ n_tty_receive_char_special(struct tty_struct *tty, unsigned char c) 
			goto handle_newline;

		}

		if (c == EOF_CHAR(tty)) {

			if (read_cnt(ldata) >= N_TTY_BUF_SIZE)

				return;

			c = __DISABLED_CHAR;

			goto handle_newline;

		}
@@ -1354,11 +1344,6 @@ n_tty_receive_char_special(struct tty_struct *tty, unsigned char c) 
		    (c == EOL2_CHAR(tty) && L_IEXTEN(tty))) {

			parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty))

				 ? 1 : 0;

			if (read_cnt(ldata) >= (N_TTY_BUF_SIZE - parmrk)) {

				if (L_ECHO(tty))

					process_output('\a', tty);

				return;

			}

			/*

			 * XXX are EOL_CHAR and EOL2_CHAR echoed?!?

			 */
@@ -1388,12 +1373,6 @@ handle_newline: 
	}



	parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0;

	if (read_cnt(ldata) >= (N_TTY_BUF_SIZE - parmrk - 1)) {

		/* beep if no space */

		if (L_ECHO(tty))

			process_output('\a', tty);

		return;

	}

	if (L_ECHO(tty)) {

		finish_erasing(ldata);

		if (c == '\n')
@@ -1432,14 +1411,6 @@ static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c) 
			start_tty(tty);

			process_echoes(tty);

		}



		parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0;

		if (read_cnt(ldata) >= (N_TTY_BUF_SIZE - parmrk - 1)) {

			/* beep if no space */

			if (L_ECHO(tty))

				process_output('\a', tty);

			return;

		}

		if (L_ECHO(tty)) {

			finish_erasing(ldata);

			/* Record the column of first canon char. */
@@ -1448,6 +1419,7 @@ static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c) 
			echo_char(c, tty);

			commit_echoes(tty);

		}

		parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0;

		if (parmrk)

			put_tty_queue(c, ldata);

		put_tty_queue(c, ldata);
@@ -1476,13 +1448,6 @@ n_tty_receive_char_fast(struct tty_struct *tty, unsigned char c) 
			start_tty(tty);

			process_echoes(tty);

		}



		if (read_cnt(ldata) >= (N_TTY_BUF_SIZE - 1)) {

			/* beep if no space */

			if (L_ECHO(tty))

				process_output('\a', tty);

			return;

		}

		if (L_ECHO(tty)) {

			finish_erasing(ldata);

			/* Record the column of first canon char. */
@@ -1691,8 +1656,23 @@ static void __receive_buf(struct tty_struct *tty, const unsigned char *cp, 
static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp,

			      char *fp, int count)

{

	int room, n;



	down_read(&tty->termios_rwsem);

	__receive_buf(tty, cp, fp, count);



	while (1) {

		room = receive_room(tty);

		n = min(count, room);

		if (!n)

			break;

		__receive_buf(tty, cp, fp, n);

		cp += n;

		if (fp)

			fp += n;

		count -= n;

	}



	tty->receive_room = room;

	n_tty_check_throttle(tty);

	up_read(&tty->termios_rwsem);

}
@@ -1701,22 +1681,31 @@ static int n_tty_receive_buf2(struct tty_struct *tty, const unsigned char *cp, 
			      char *fp, int count)

{

	struct n_tty_data *ldata = tty->disc_data;

	int room;

	int room, n, rcvd = 0;



	down_read(&tty->termios_rwsem);



	tty->receive_room = room = receive_room(tty);

	while (1) {

		room = receive_room(tty);

		n = min(count, room);

		if (!n) {

			if (!room)

				ldata->no_room = 1;

	count = min(count, room);

	if (count) {

		__receive_buf(tty, cp, fp, count);

		n_tty_check_throttle(tty);

			break;

		}

		__receive_buf(tty, cp, fp, n);

		cp += n;

		if (fp)

			fp += n;

		count -= n;

		rcvd += n;

	}



	tty->receive_room = room;

	n_tty_check_throttle(tty);

	up_read(&tty->termios_rwsem);



	return count;

	return rcvd;

}



int is_ignored(int sig)

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