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ati-vga: Fix checks in ati_2d_blt() to avoid crash

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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>
This commit is contained in:
BALATON Zoltan 2020-04-06 22:34:26 +02:00 committed by Gerd Hoffmann
parent 8d1439b692
commit ac2071c379
1 changed files with 26 additions and 11 deletions
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29
hw/display/ati_2d.c
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@ -53,12 +53,20 @@ void ati_2d_blt(ATIVGAState *s)
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 ?
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);
int dst_y = (s->regs.dp_cntl & DST_Y_TOP_TO_BOTTOM ?
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 @@ void ati_2d_blt(ATIVGAState *s)
switch (s->regs.dp_mix & GMC_ROP3_MASK) {
case ROP3_SRCCOPY:
{
int src_x = (s->regs.dp_cntl & DST_X_LEFT_TO_RIGHT ?
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);
int src_y = (s->regs.dp_cntl & DST_Y_TOP_TO_BOTTOM ?
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 @@ void ati_2d_blt(ATIVGAState *s)
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 @@ void ati_2d_blt(ATIVGAState *s)
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: