From: Yangxi Xiang xyangxi5@gmail.com

[ upstream commit 39cdb68c64d8 ]

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 stable@kernel.org Signed-off-by: Yangxi Xiang xyangxi5@gmail.com Link: https://lore.kernel.org/r/20220628093322.5688-1-xyangxi5@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org [ KN: vc_state is not a separate structure in LTS v4.19, v5.4. Adjusted the patch accordingly by using vc_x instead of state.x for backport. ] Signed-off-by: Kuntal Nayak kuntal.nayak@broadcom.com --- 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 c9083d853..a351e264d 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->vc_x - nr) * 2); + scr_memmovew(p, p + nr, (vc->vc_cols - vc->vc_x - nr) * 2); scr_memsetw(p + vc->vc_cols - vc->vc_x - nr, vc->vc_video_erase_char, nr * 2); vc->vc_need_wrap = 0;