Re: [Qemu-devel] [PATCH v2 2/2] ati: use vga_read_byte in ati_cursor_define

[BALATON Zoltan]

On Fri, 13 Sep 2019, Gerd Hoffmann wrote:
> This makes sure reads are confined to vga video memory.
>
> v2: fix ati_cursor_draw_line too.
>
> Reported-by: xu hang <address@hidden>
> Signed-off-by: Gerd Hoffmann <address@hidden>
> ---
> hw/display/ati.c | 19 ++++++++++---------
> 1 file changed, 10 insertions(+), 9 deletions(-)
>
> diff --git a/hw/display/ati.c b/hw/display/ati.c
> index 8f940eee221a..f6ae27c0c710 100644
> --- a/hw/display/ati.c
> +++ b/hw/display/ati.c
> @@ -19,6 +19,7 @@
> #include "qemu/osdep.h"
> #include "ati_int.h"
> #include "ati_regs.h"
> +#include "vga-access.h"
> #include "hw/qdev-properties.h"
> #include "vga_regs.h"
> #include "qemu/log.h"
> @@ -135,19 +136,19 @@ static void ati_vga_switch_mode(ATIVGAState *s)
> static void ati_cursor_define(ATIVGAState *s)
> {
>     uint8_t data[1024];
> -    uint8_t *src;
> +    unsigned srcoff;

Maybe this should be uint32_t like below for consistency.

>     int i, j, idx = 0;
>
>     if ((s->regs.cur_offset & BIT(31)) || s->cursor_guest_mode) {
>         return; /* Do not update cursor if locked or rendered by guest */
>     }
>     /* FIXME handle cur_hv_offs correctly */
> -    src = s->vga.vram_ptr + s->regs.cur_offset -
> -          (s->regs.cur_hv_offs >> 16) - (s->regs.cur_hv_offs & 0xffff) * 16;
> +    srcoff = s->regs.cur_offset -
> +        (s->regs.cur_hv_offs >> 16) - (s->regs.cur_hv_offs & 0xffff) * 16;
>     for (i = 0; i < 64; i++) {
>         for (j = 0; j < 8; j++, idx++) {
> -            data[idx] = src[i * 16 + j];
> -            data[512 + idx] = src[i * 16 + j + 8];
> +            data[idx] = vga_read_byte(&s->vga, srcoff + i * 16 + j);
> +            data[512 + idx] = vga_read_byte(&s->vga, srcoff + i * 16 + j + 8);
>         }
>     }
>     if (!s->cursor) {
> @@ -189,7 +190,7 @@ static void ati_cursor_invalidate(VGACommonState *vga)
> static void ati_cursor_draw_line(VGACommonState *vga, uint8_t *d, int scr_y)
> {
>     ATIVGAState *s = container_of(vga, ATIVGAState, vga);
> -    uint8_t *src;
> +    uint32_t srcoff;
>     uint32_t *dp = (uint32_t *)d;
>     int i, j, h;
>
> @@ -199,13 +200,13 @@ static void ati_cursor_draw_line(VGACommonState *vga, 
> uint8_t *d, int scr_y)
>         return;
>     }
>     /* FIXME handle cur_hv_offs correctly */
> -    src = s->vga.vram_ptr + s->cursor_offset + (scr_y - vga->hw_cursor_y) * 16;
> +    srcoff = s->cursor_offset + (scr_y - vga->hw_cursor_y) * 16;
>     dp = &dp[vga->hw_cursor_x];
>     h = ((s->regs.crtc_h_total_disp >> 16) + 1) * 8;
>     for (i = 0; i < 8; i++) {
>         uint32_t color;
> -        uint8_t abits = src[i];
> -        uint8_t xbits = src[i + 8];
> +        uint8_t abits = vga_read_byte(vga, srcoff + i);
> +        uint8_t xbits = vga_read_byte(vga, srcoff + i);

But this is a copy&paste error: xbits definitely should be offset + i + 8.

Regards,
BALATON Zoltan

>         for (j = 0; j < 8; j++, abits <<= 1, xbits <<= 1) {
>             if (abits & BIT(7)) {
>                 if (xbits & BIT(7)) {