Commit 6f222536 authored Nov 08, 2013 by Peter Hurley Committed by Greg Kroah-Hartman Nov 25, 2013

n_tty: Fix echo overrun tail computation



Commit cbfd0340,
'n_tty: Process echoes in blocks', introduced an error when
consuming the echo buffer tail to prevent buffer overrun, where
the incorrect operation code byte is checked to determine how
far to advance the tail to the next echo byte.

Check the correct byte for the echo operation code byte.

Cc: <stable@vger.kernel.org> # 3.12.x : c476f658 tty: incorrect test of echo_buf() result for ECHO_OP_START
Cc: <stable@vger.kernel.org> # 3.12.x
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 42458f41

drivers/tty/n_tty.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -768,7 +768,7 @@ static size_t __process_echoes(struct tty_struct *tty)
		* data at the tail to prevent a subsequent overrun */
		while (ldata->echo_commit - tail >= ECHO_DISCARD_WATERMARK) {
		if (echo_buf(ldata, tail) == ECHO_OP_START) {
		if (echo_buf(ldata, tail) == ECHO_OP_ERASE_TAB)
		if (echo_buf(ldata, tail + 1) == ECHO_OP_ERASE_TAB)
		tail += 3;
		else
		tail += 2;

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