linux-kernel - [PATCH] auxdisplay: charlcd: fix x/y command parsing

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Message-Id: <20181205135247.7964-1-mans@mansr.com>
Date:   Wed,  5 Dec 2018 13:52:47 +0000
From:   Mans Rullgard <mans@...sr.com>
To:     Miguel Ojeda Sandonis <miguel.ojeda.sandonis@...il.com>
Cc:     linux-kernel@...r.kernel.org
Subject: [PATCH] auxdisplay: charlcd: fix x/y command parsing

Commit b34050fadb86 ("auxdisplay: charlcd: Fix and clean up handling of
x/y commands") fixed some problems by rewriting the parsing code,
but also broke things further by removing the check for a complete
command before attempting to parse it.  As a result, parsing is
terminated at the first x or y character.

This reinstates the check for a final semicolon.  Whereas the original
code use strchr(), this is wasteful seeing as the semicolon is always
at the end of the buffer.  Thus check this character directly instead.

Signed-off-by: Mans Rullgard <mans@...sr.com>
---
 drivers/auxdisplay/charlcd.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/auxdisplay/charlcd.c b/drivers/auxdisplay/charlcd.c
index 81c22d20d9d9..60e0b772673f 100644
--- a/drivers/auxdisplay/charlcd.c
+++ b/drivers/auxdisplay/charlcd.c
@@ -538,6 +538,9 @@ static inline int handle_lcd_special_code(struct charlcd *lcd)
 	}
 	case 'x':	/* gotoxy : LxXXX[yYYY]; */
 	case 'y':	/* gotoxy : LyYYY[xXXX]; */
+		if (priv->esc_seq.buf[priv->esc_seq.len - 1] != ';')
+			break;
+
 		/* If the command is valid, move to the new address */
 		if (parse_xy(esc, &priv->addr.x, &priv->addr.y))
 			charlcd_gotoxy(lcd);
-- 
2.19.2