From 6f2225363c205e186c1465c2c7c84f17c1635504 Mon Sep 17 00:00:00 2001 From: Peter Hurley Date: Fri, 8 Nov 2013 09:42:18 -0500 Subject: [PATCH] n_tty: Fix echo overrun tail computation Commit cbfd0340ae1993378fd47179db949e050e16e697, '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: # 3.12.x : c476f65 tty: incorrect test of echo_buf() result for ECHO_OP_START Cc: # 3.12.x Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman --- drivers/tty/n_tty.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c index a2b70c97391f..d8a779d3a611 100644 --- a/drivers/tty/n_tty.c +++ b/drivers/tty/n_tty.c @@ -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;