ati-vga: Fix checks in ati_2d_blt() to avoid crash
In some corner cases (that never happen during normal operation but a
malicious guest could program wrong values) pixman functions were
called with parameters that result in a crash. Fix this and add more
checks to disallow such cases.
Reported-by: Ziming Zhang <ezrakiez@gmail.com>
Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu>
Message-id: 20200406204029.19559747D5D@zero.eik.bme.hu
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
diff --git a/hw/display/ati_2d.c b/hw/display/ati_2d.c
index 42e8231..23a8ae0 100644
--- a/hw/display/ati_2d.c
+++ b/hw/display/ati_2d.c
@@ -53,12 +53,20 @@
s->vga.vbe_start_addr, surface_data(ds), surface_stride(ds),
surface_bits_per_pixel(ds),
(s->regs.dp_mix & GMC_ROP3_MASK) >> 16);
- int dst_x = (s->regs.dp_cntl & DST_X_LEFT_TO_RIGHT ?
- s->regs.dst_x : s->regs.dst_x + 1 - s->regs.dst_width);
- int dst_y = (s->regs.dp_cntl & DST_Y_TOP_TO_BOTTOM ?
- s->regs.dst_y : s->regs.dst_y + 1 - s->regs.dst_height);
+ unsigned dst_x = (s->regs.dp_cntl & DST_X_LEFT_TO_RIGHT ?
+ s->regs.dst_x : s->regs.dst_x + 1 - s->regs.dst_width);
+ unsigned dst_y = (s->regs.dp_cntl & DST_Y_TOP_TO_BOTTOM ?
+ s->regs.dst_y : s->regs.dst_y + 1 - s->regs.dst_height);
int bpp = ati_bpp_from_datatype(s);
+ if (!bpp) {
+ qemu_log_mask(LOG_GUEST_ERROR, "Invalid bpp\n");
+ return;
+ }
int dst_stride = DEFAULT_CNTL ? s->regs.dst_pitch : s->regs.default_pitch;
+ if (!dst_stride) {
+ qemu_log_mask(LOG_GUEST_ERROR, "Zero dest pitch\n");
+ return;
+ }
uint8_t *dst_bits = s->vga.vram_ptr + (DEFAULT_CNTL ?
s->regs.dst_offset : s->regs.default_offset);
@@ -82,12 +90,16 @@
switch (s->regs.dp_mix & GMC_ROP3_MASK) {
case ROP3_SRCCOPY:
{
- int src_x = (s->regs.dp_cntl & DST_X_LEFT_TO_RIGHT ?
- s->regs.src_x : s->regs.src_x + 1 - s->regs.dst_width);
- int src_y = (s->regs.dp_cntl & DST_Y_TOP_TO_BOTTOM ?
- s->regs.src_y : s->regs.src_y + 1 - s->regs.dst_height);
+ unsigned src_x = (s->regs.dp_cntl & DST_X_LEFT_TO_RIGHT ?
+ s->regs.src_x : s->regs.src_x + 1 - s->regs.dst_width);
+ unsigned src_y = (s->regs.dp_cntl & DST_Y_TOP_TO_BOTTOM ?
+ s->regs.src_y : s->regs.src_y + 1 - s->regs.dst_height);
int src_stride = DEFAULT_CNTL ?
s->regs.src_pitch : s->regs.default_pitch;
+ if (!src_stride) {
+ qemu_log_mask(LOG_GUEST_ERROR, "Zero source pitch\n");
+ return;
+ }
uint8_t *src_bits = s->vga.vram_ptr + (DEFAULT_CNTL ?
s->regs.src_offset : s->regs.default_offset);
@@ -137,8 +149,10 @@
dst_y * surface_stride(ds),
s->regs.dst_height * surface_stride(ds));
}
- s->regs.dst_x += s->regs.dst_width;
- s->regs.dst_y += s->regs.dst_height;
+ s->regs.dst_x = (s->regs.dp_cntl & DST_X_LEFT_TO_RIGHT ?
+ dst_x + s->regs.dst_width : dst_x);
+ s->regs.dst_y = (s->regs.dp_cntl & DST_Y_TOP_TO_BOTTOM ?
+ dst_y + s->regs.dst_height : dst_y);
break;
}
case ROP3_PATCOPY:
@@ -179,7 +193,8 @@
dst_y * surface_stride(ds),
s->regs.dst_height * surface_stride(ds));
}
- s->regs.dst_y += s->regs.dst_height;
+ s->regs.dst_y = (s->regs.dp_cntl & DST_Y_TOP_TO_BOTTOM ?
+ dst_y + s->regs.dst_height : dst_y);
break;
}
default:
