From 7e5104153e5fa95f7cf10879c2a58290929c6fc5 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 1d0cca54b1dd573e06e3ed34db6751394f8e132d, '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 : 4f89454 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 a2b70c97391f2..d8a779d3a611e 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; -- 2.39.5