From 57964a5710252bc82fe22d9fa98c180c58c20244 Mon Sep 17 00:00:00 2001 From: Yangxi Xiang Date: Tue, 28 Jun 2022 17:33:22 +0800 Subject: [PATCH] vt: fix memory overlapping when deleting chars in the buffer commit 39cdb68c64d84e71a4a717000b6e5de208ee60cc upstream. A memory overlapping copy occurs when deleting a long line. This memory overlapping copy can cause data corruption when scr_memcpyw is optimized to memcpy because memcpy does not ensure its behavior if the destination buffer overlaps with the source buffer. The line buffer is not always broken, because the memcpy utilizes the hardware acceleration, whose result is not deterministic. Fix this problem by using replacing the scr_memcpyw with scr_memmovew. Fixes: 81732c3b2fed ("tty vt: Fix line garbage in virtual console on command line edition") Cc: stable Signed-off-by: Yangxi Xiang Link: https://lore.kernel.org/r/20220628093322.5688-1-xyangxi5@gmail.com Signed-off-by: Greg Kroah-Hartman --- drivers/tty/vt/vt.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c index 7359c3e..55283a7 100644 --- a/drivers/tty/vt/vt.c +++ b/drivers/tty/vt/vt.c @@ -855,7 +855,7 @@ static void delete_char(struct vc_data *vc, unsigned int nr) unsigned short *p = (unsigned short *) vc->vc_pos; vc_uniscr_delete(vc, nr); - scr_memcpyw(p, p + nr, (vc->vc_cols - vc->state.x - nr) * 2); + scr_memmovew(p, p + nr, (vc->vc_cols - vc->state.x - nr) * 2); scr_memsetw(p + vc->vc_cols - vc->state.x - nr, vc->vc_video_erase_char, nr * 2); vc->vc_need_wrap = 0; -- 2.7.4