[PATCH AUTOSEL 4.19 97/97] auxdisplay: charlcd: fix x/y command parsing

From: Sasha Levin
Date: Wed Dec 26 2018 - 17:39:10 EST

From: Mans Rullgard <mans@xxxxxxxxx>

[ Upstream commit 9bc30ab82108e6a34dc63bf956b49edf71b1681a ]

The x/y command parsing has been broken since commit 129957069e6a
("staging: panel: Fixed checkpatch warning about simple_strtoul()").

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@xxxxxxxxx>
Signed-off-by: Miguel Ojeda <miguel.ojeda.sandonis@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
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))