vga: stop passing pointers to vga_draw_line* functions
Instead pass around the address (aka offset into vga memory).
Add vga_read_* helper functions which apply vbe_size_mask to
the address, to make sure the address stays within the valid
range, similar to the cirrus blitter fixes (commits ffaf857778
and 026aeffcb4).
Impact: DoS for privileged guest users. qemu crashes with
a segfault, when hitting the guard page after vga memory
allocation, while reading vga memory for display updates.
Fixes: CVE-2017-13672
Cc: P J P <ppandit@redhat.com>
Reported-by: David Buchanan <d@vidbuchanan.co.uk>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Message-id: 20170828122906.18993-1-kraxel@redhat.com
diff --git a/hw/display/vga-helpers.h b/hw/display/vga-helpers.h
index 94f6de2..5a752b3 100644
--- a/hw/display/vga-helpers.h
+++ b/hw/display/vga-helpers.h
@@ -95,20 +95,46 @@
} while (--h);
}
+static inline uint8_t vga_read_byte(VGACommonState *vga, uint32_t addr)
+{
+ return vga->vram_ptr[addr & vga->vbe_size_mask];
+}
+
+static inline uint16_t vga_read_word_le(VGACommonState *vga, uint32_t addr)
+{
+ uint32_t offset = addr & vga->vbe_size_mask & ~1;
+ uint16_t *ptr = (uint16_t *)(vga->vram_ptr + offset);
+ return lduw_le_p(ptr);
+}
+
+static inline uint16_t vga_read_word_be(VGACommonState *vga, uint32_t addr)
+{
+ uint32_t offset = addr & vga->vbe_size_mask & ~1;
+ uint16_t *ptr = (uint16_t *)(vga->vram_ptr + offset);
+ return lduw_be_p(ptr);
+}
+
+static inline uint32_t vga_read_dword_le(VGACommonState *vga, uint32_t addr)
+{
+ uint32_t offset = addr & vga->vbe_size_mask & ~3;
+ uint32_t *ptr = (uint32_t *)(vga->vram_ptr + offset);
+ return ldl_le_p(ptr);
+}
+
/*
* 4 color mode
*/
-static void vga_draw_line2(VGACommonState *s1, uint8_t *d,
- const uint8_t *s, int width)
+static void vga_draw_line2(VGACommonState *vga, uint8_t *d,
+ uint32_t addr, int width)
{
uint32_t plane_mask, *palette, data, v;
int x;
- palette = s1->last_palette;
- plane_mask = mask16[s1->ar[VGA_ATC_PLANE_ENABLE] & 0xf];
+ palette = vga->last_palette;
+ plane_mask = mask16[vga->ar[VGA_ATC_PLANE_ENABLE] & 0xf];
width >>= 3;
for(x = 0; x < width; x++) {
- data = ((uint32_t *)s)[0];
+ data = vga_read_dword_le(vga, addr);
data &= plane_mask;
v = expand2[GET_PLANE(data, 0)];
v |= expand2[GET_PLANE(data, 2)] << 2;
@@ -124,7 +150,7 @@
((uint32_t *)d)[6] = palette[(v >> 4) & 0xf];
((uint32_t *)d)[7] = palette[(v >> 0) & 0xf];
d += 32;
- s += 4;
+ addr += 4;
}
}
@@ -134,17 +160,17 @@
/*
* 4 color mode, dup2 horizontal
*/
-static void vga_draw_line2d2(VGACommonState *s1, uint8_t *d,
- const uint8_t *s, int width)
+static void vga_draw_line2d2(VGACommonState *vga, uint8_t *d,
+ uint32_t addr, int width)
{
uint32_t plane_mask, *palette, data, v;
int x;
- palette = s1->last_palette;
- plane_mask = mask16[s1->ar[VGA_ATC_PLANE_ENABLE] & 0xf];
+ palette = vga->last_palette;
+ plane_mask = mask16[vga->ar[VGA_ATC_PLANE_ENABLE] & 0xf];
width >>= 3;
for(x = 0; x < width; x++) {
- data = ((uint32_t *)s)[0];
+ data = vga_read_dword_le(vga, addr);
data &= plane_mask;
v = expand2[GET_PLANE(data, 0)];
v |= expand2[GET_PLANE(data, 2)] << 2;
@@ -160,24 +186,24 @@
PUT_PIXEL2(d, 6, palette[(v >> 4) & 0xf]);
PUT_PIXEL2(d, 7, palette[(v >> 0) & 0xf]);
d += 64;
- s += 4;
+ addr += 4;
}
}
/*
* 16 color mode
*/
-static void vga_draw_line4(VGACommonState *s1, uint8_t *d,
- const uint8_t *s, int width)
+static void vga_draw_line4(VGACommonState *vga, uint8_t *d,
+ uint32_t addr, int width)
{
uint32_t plane_mask, data, v, *palette;
int x;
- palette = s1->last_palette;
- plane_mask = mask16[s1->ar[VGA_ATC_PLANE_ENABLE] & 0xf];
+ palette = vga->last_palette;
+ plane_mask = mask16[vga->ar[VGA_ATC_PLANE_ENABLE] & 0xf];
width >>= 3;
for(x = 0; x < width; x++) {
- data = ((uint32_t *)s)[0];
+ data = vga_read_dword_le(vga, addr);
data &= plane_mask;
v = expand4[GET_PLANE(data, 0)];
v |= expand4[GET_PLANE(data, 1)] << 1;
@@ -192,24 +218,24 @@
((uint32_t *)d)[6] = palette[(v >> 4) & 0xf];
((uint32_t *)d)[7] = palette[(v >> 0) & 0xf];
d += 32;
- s += 4;
+ addr += 4;
}
}
/*
* 16 color mode, dup2 horizontal
*/
-static void vga_draw_line4d2(VGACommonState *s1, uint8_t *d,
- const uint8_t *s, int width)
+static void vga_draw_line4d2(VGACommonState *vga, uint8_t *d,
+ uint32_t addr, int width)
{
uint32_t plane_mask, data, v, *palette;
int x;
- palette = s1->last_palette;
- plane_mask = mask16[s1->ar[VGA_ATC_PLANE_ENABLE] & 0xf];
+ palette = vga->last_palette;
+ plane_mask = mask16[vga->ar[VGA_ATC_PLANE_ENABLE] & 0xf];
width >>= 3;
for(x = 0; x < width; x++) {
- data = ((uint32_t *)s)[0];
+ data = vga_read_dword_le(vga, addr);
data &= plane_mask;
v = expand4[GET_PLANE(data, 0)];
v |= expand4[GET_PLANE(data, 1)] << 1;
@@ -224,7 +250,7 @@
PUT_PIXEL2(d, 6, palette[(v >> 4) & 0xf]);
PUT_PIXEL2(d, 7, palette[(v >> 0) & 0xf]);
d += 64;
- s += 4;
+ addr += 4;
}
}
@@ -233,21 +259,21 @@
*
* XXX: add plane_mask support (never used in standard VGA modes)
*/
-static void vga_draw_line8d2(VGACommonState *s1, uint8_t *d,
- const uint8_t *s, int width)
+static void vga_draw_line8d2(VGACommonState *vga, uint8_t *d,
+ uint32_t addr, int width)
{
uint32_t *palette;
int x;
- palette = s1->last_palette;
+ palette = vga->last_palette;
width >>= 3;
for(x = 0; x < width; x++) {
- PUT_PIXEL2(d, 0, palette[s[0]]);
- PUT_PIXEL2(d, 1, palette[s[1]]);
- PUT_PIXEL2(d, 2, palette[s[2]]);
- PUT_PIXEL2(d, 3, palette[s[3]]);
+ PUT_PIXEL2(d, 0, palette[vga_read_byte(vga, addr + 0)]);
+ PUT_PIXEL2(d, 1, palette[vga_read_byte(vga, addr + 1)]);
+ PUT_PIXEL2(d, 2, palette[vga_read_byte(vga, addr + 2)]);
+ PUT_PIXEL2(d, 3, palette[vga_read_byte(vga, addr + 3)]);
d += 32;
- s += 4;
+ addr += 4;
}
}
@@ -256,63 +282,63 @@
*
* XXX: add plane_mask support (never used in standard VGA modes)
*/
-static void vga_draw_line8(VGACommonState *s1, uint8_t *d,
- const uint8_t *s, int width)
+static void vga_draw_line8(VGACommonState *vga, uint8_t *d,
+ uint32_t addr, int width)
{
uint32_t *palette;
int x;
- palette = s1->last_palette;
+ palette = vga->last_palette;
width >>= 3;
for(x = 0; x < width; x++) {
- ((uint32_t *)d)[0] = palette[s[0]];
- ((uint32_t *)d)[1] = palette[s[1]];
- ((uint32_t *)d)[2] = palette[s[2]];
- ((uint32_t *)d)[3] = palette[s[3]];
- ((uint32_t *)d)[4] = palette[s[4]];
- ((uint32_t *)d)[5] = palette[s[5]];
- ((uint32_t *)d)[6] = palette[s[6]];
- ((uint32_t *)d)[7] = palette[s[7]];
+ ((uint32_t *)d)[0] = palette[vga_read_byte(vga, addr + 0)];
+ ((uint32_t *)d)[1] = palette[vga_read_byte(vga, addr + 1)];
+ ((uint32_t *)d)[2] = palette[vga_read_byte(vga, addr + 2)];
+ ((uint32_t *)d)[3] = palette[vga_read_byte(vga, addr + 3)];
+ ((uint32_t *)d)[4] = palette[vga_read_byte(vga, addr + 4)];
+ ((uint32_t *)d)[5] = palette[vga_read_byte(vga, addr + 5)];
+ ((uint32_t *)d)[6] = palette[vga_read_byte(vga, addr + 6)];
+ ((uint32_t *)d)[7] = palette[vga_read_byte(vga, addr + 7)];
d += 32;
- s += 8;
+ addr += 8;
}
}
/*
* 15 bit color
*/
-static void vga_draw_line15_le(VGACommonState *s1, uint8_t *d,
- const uint8_t *s, int width)
+static void vga_draw_line15_le(VGACommonState *vga, uint8_t *d,
+ uint32_t addr, int width)
{
int w;
uint32_t v, r, g, b;
w = width;
do {
- v = lduw_le_p((void *)s);
+ v = vga_read_word_le(vga, addr);
r = (v >> 7) & 0xf8;
g = (v >> 2) & 0xf8;
b = (v << 3) & 0xf8;
((uint32_t *)d)[0] = rgb_to_pixel32(r, g, b);
- s += 2;
+ addr += 2;
d += 4;
} while (--w != 0);
}
-static void vga_draw_line15_be(VGACommonState *s1, uint8_t *d,
- const uint8_t *s, int width)
+static void vga_draw_line15_be(VGACommonState *vga, uint8_t *d,
+ uint32_t addr, int width)
{
int w;
uint32_t v, r, g, b;
w = width;
do {
- v = lduw_be_p((void *)s);
+ v = vga_read_word_be(vga, addr);
r = (v >> 7) & 0xf8;
g = (v >> 2) & 0xf8;
b = (v << 3) & 0xf8;
((uint32_t *)d)[0] = rgb_to_pixel32(r, g, b);
- s += 2;
+ addr += 2;
d += 4;
} while (--w != 0);
}
@@ -320,38 +346,38 @@
/*
* 16 bit color
*/
-static void vga_draw_line16_le(VGACommonState *s1, uint8_t *d,
- const uint8_t *s, int width)
+static void vga_draw_line16_le(VGACommonState *vga, uint8_t *d,
+ uint32_t addr, int width)
{
int w;
uint32_t v, r, g, b;
w = width;
do {
- v = lduw_le_p((void *)s);
+ v = vga_read_word_le(vga, addr);
r = (v >> 8) & 0xf8;
g = (v >> 3) & 0xfc;
b = (v << 3) & 0xf8;
((uint32_t *)d)[0] = rgb_to_pixel32(r, g, b);
- s += 2;
+ addr += 2;
d += 4;
} while (--w != 0);
}
-static void vga_draw_line16_be(VGACommonState *s1, uint8_t *d,
- const uint8_t *s, int width)
+static void vga_draw_line16_be(VGACommonState *vga, uint8_t *d,
+ uint32_t addr, int width)
{
int w;
uint32_t v, r, g, b;
w = width;
do {
- v = lduw_be_p((void *)s);
+ v = vga_read_word_be(vga, addr);
r = (v >> 8) & 0xf8;
g = (v >> 3) & 0xfc;
b = (v << 3) & 0xf8;
((uint32_t *)d)[0] = rgb_to_pixel32(r, g, b);
- s += 2;
+ addr += 2;
d += 4;
} while (--w != 0);
}
@@ -359,36 +385,36 @@
/*
* 24 bit color
*/
-static void vga_draw_line24_le(VGACommonState *s1, uint8_t *d,
- const uint8_t *s, int width)
+static void vga_draw_line24_le(VGACommonState *vga, uint8_t *d,
+ uint32_t addr, int width)
{
int w;
uint32_t r, g, b;
w = width;
do {
- b = s[0];
- g = s[1];
- r = s[2];
+ b = vga_read_byte(vga, addr + 0);
+ g = vga_read_byte(vga, addr + 1);
+ r = vga_read_byte(vga, addr + 2);
((uint32_t *)d)[0] = rgb_to_pixel32(r, g, b);
- s += 3;
+ addr += 3;
d += 4;
} while (--w != 0);
}
-static void vga_draw_line24_be(VGACommonState *s1, uint8_t *d,
- const uint8_t *s, int width)
+static void vga_draw_line24_be(VGACommonState *vga, uint8_t *d,
+ uint32_t addr, int width)
{
int w;
uint32_t r, g, b;
w = width;
do {
- r = s[0];
- g = s[1];
- b = s[2];
+ r = vga_read_byte(vga, addr + 0);
+ g = vga_read_byte(vga, addr + 1);
+ b = vga_read_byte(vga, addr + 2);
((uint32_t *)d)[0] = rgb_to_pixel32(r, g, b);
- s += 3;
+ addr += 3;
d += 4;
} while (--w != 0);
}
@@ -396,44 +422,36 @@
/*
* 32 bit color
*/
-static void vga_draw_line32_le(VGACommonState *s1, uint8_t *d,
- const uint8_t *s, int width)
+static void vga_draw_line32_le(VGACommonState *vga, uint8_t *d,
+ uint32_t addr, int width)
{
-#ifndef HOST_WORDS_BIGENDIAN
- memcpy(d, s, width * 4);
-#else
int w;
uint32_t r, g, b;
w = width;
do {
- b = s[0];
- g = s[1];
- r = s[2];
+ b = vga_read_byte(vga, addr + 0);
+ g = vga_read_byte(vga, addr + 1);
+ r = vga_read_byte(vga, addr + 2);
((uint32_t *)d)[0] = rgb_to_pixel32(r, g, b);
- s += 4;
+ addr += 4;
d += 4;
} while (--w != 0);
-#endif
}
-static void vga_draw_line32_be(VGACommonState *s1, uint8_t *d,
- const uint8_t *s, int width)
+static void vga_draw_line32_be(VGACommonState *vga, uint8_t *d,
+ uint32_t addr, int width)
{
-#ifdef HOST_WORDS_BIGENDIAN
- memcpy(d, s, width * 4);
-#else
int w;
uint32_t r, g, b;
w = width;
do {
- r = s[1];
- g = s[2];
- b = s[3];
+ r = vga_read_byte(vga, addr + 1);
+ g = vga_read_byte(vga, addr + 2);
+ b = vga_read_byte(vga, addr + 3);
((uint32_t *)d)[0] = rgb_to_pixel32(r, g, b);
- s += 4;
+ addr += 4;
d += 4;
} while (--w != 0);
-#endif
}
