[PATCH] vt: fix memory overlapping when deleting chars in the buffer

From: Yangxi Xiang
Date: Mon Jun 27 2022 - 06:29:49 EST


A memory overlapping copy occurs when deleting a long line. Fix it by
using scr_memmovew.

Signed-off-by: Yangxi Xiang <xyangxi5@xxxxxxxxx>
---
drivers/tty/vt/vt.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index f8c87c4d7399..d87bff9d8ed5 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -853,9 +853,13 @@ static void insert_char(struct vc_data *vc, unsigned int nr)
static void delete_char(struct vc_data *vc, unsigned int nr)
{
unsigned short *p = (unsigned short *) vc->vc_pos;
+ unsigned short cp = (vc->vc_cols - vc->state.x - nr) * 2;

vc_uniscr_delete(vc, nr);
- scr_memcpyw(p, p + nr, (vc->vc_cols - vc->state.x - nr) * 2);
+ if (cp > nr)
+ scr_memmovew(p, p + nr, cp);
+ else
+ scr_memcpyw(p, p + nr, cp);
scr_memsetw(p + vc->vc_cols - vc->state.x - nr, vc->vc_video_erase_char,
nr * 2);
vc->vc_need_wrap = 0;
--
2.17.1