CVE-2007-1320 - Cirrus LGD-54XX "bitblt" heap overflow
I have just noticed that patch for CVE-2007-1320 has never been applied
to the QEMU CVS. Please find it below.
| Multiple heap-based buffer overflows in the cirrus_invalidate_region
| function in the Cirrus VGA extension in QEMU 0.8.2, as used in Xen and
| possibly other products, might allow local users to execute arbitrary
| code via unspecified vectors related to "attempting to mark
| non-existent regions as dirty," aka the "bitblt" heap overflow.
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@4340 c046a42c-6fe2-441c-8c8c-71466251a162
diff --git a/hw/cirrus_vga.c b/hw/cirrus_vga.c
index 07e52b0..47acb32 100644
--- a/hw/cirrus_vga.c
+++ b/hw/cirrus_vga.c
@@ -220,6 +220,20 @@
#define CIRRUS_HOOK_NOT_HANDLED 0
#define CIRRUS_HOOK_HANDLED 1
+#define BLTUNSAFE(s) \
+ ( \
+ ( /* check dst is within bounds */ \
+ (s)->cirrus_blt_height * (s)->cirrus_blt_dstpitch \
+ + ((s)->cirrus_blt_dstaddr & (s)->cirrus_addr_mask) > \
+ (s)->vram_size \
+ ) || \
+ ( /* check src is within bounds */ \
+ (s)->cirrus_blt_height * (s)->cirrus_blt_srcpitch \
+ + ((s)->cirrus_blt_srcaddr & (s)->cirrus_addr_mask) > \
+ (s)->vram_size \
+ ) \
+ )
+
struct CirrusVGAState;
typedef void (*cirrus_bitblt_rop_t) (struct CirrusVGAState *s,
uint8_t * dst, const uint8_t * src,
@@ -639,7 +653,7 @@
for (y = 0; y < lines; y++) {
off_cur = off_begin;
- off_cur_end = off_cur + bytesperline;
+ off_cur_end = (off_cur + bytesperline) & s->cirrus_addr_mask;
off_cur &= TARGET_PAGE_MASK;
while (off_cur < off_cur_end) {
cpu_physical_memory_set_dirty(s->vram_offset + off_cur);
@@ -654,7 +668,11 @@
{
uint8_t *dst;
- dst = s->vram_ptr + s->cirrus_blt_dstaddr;
+ dst = s->vram_ptr + (s->cirrus_blt_dstaddr & s->cirrus_addr_mask);
+
+ if (BLTUNSAFE(s))
+ return 0;
+
(*s->cirrus_rop) (s, dst, src,
s->cirrus_blt_dstpitch, 0,
s->cirrus_blt_width, s->cirrus_blt_height);
@@ -670,8 +688,10 @@
{
cirrus_fill_t rop_func;
+ if (BLTUNSAFE(s))
+ return 0;
rop_func = cirrus_fill[rop_to_index[blt_rop]][s->cirrus_blt_pixelwidth - 1];
- rop_func(s, s->vram_ptr + s->cirrus_blt_dstaddr,
+ rop_func(s, s->vram_ptr + (s->cirrus_blt_dstaddr & s->cirrus_addr_mask),
s->cirrus_blt_dstpitch,
s->cirrus_blt_width, s->cirrus_blt_height);
cirrus_invalidate_region(s, s->cirrus_blt_dstaddr,
@@ -690,8 +710,8 @@
static int cirrus_bitblt_videotovideo_patterncopy(CirrusVGAState * s)
{
return cirrus_bitblt_common_patterncopy(s,
- s->vram_ptr +
- (s->cirrus_blt_srcaddr & ~7));
+ s->vram_ptr + ((s->cirrus_blt_srcaddr & ~7) &
+ s->cirrus_addr_mask));
}
static void cirrus_do_copy(CirrusVGAState *s, int dst, int src, int w, int h)
@@ -741,8 +761,10 @@
if (notify)
vga_hw_update();
- (*s->cirrus_rop) (s, s->vram_ptr + s->cirrus_blt_dstaddr,
- s->vram_ptr + s->cirrus_blt_srcaddr,
+ (*s->cirrus_rop) (s, s->vram_ptr +
+ (s->cirrus_blt_dstaddr & s->cirrus_addr_mask),
+ s->vram_ptr +
+ (s->cirrus_blt_srcaddr & s->cirrus_addr_mask),
s->cirrus_blt_dstpitch, s->cirrus_blt_srcpitch,
s->cirrus_blt_width, s->cirrus_blt_height);
@@ -768,8 +790,14 @@
s->cirrus_blt_srcaddr - s->start_addr,
s->cirrus_blt_width, s->cirrus_blt_height);
} else {
- (*s->cirrus_rop) (s, s->vram_ptr + s->cirrus_blt_dstaddr,
- s->vram_ptr + s->cirrus_blt_srcaddr,
+
+ if (BLTUNSAFE(s))
+ return 0;
+
+ (*s->cirrus_rop) (s, s->vram_ptr +
+ (s->cirrus_blt_dstaddr & s->cirrus_addr_mask),
+ s->vram_ptr +
+ (s->cirrus_blt_srcaddr & s->cirrus_addr_mask),
s->cirrus_blt_dstpitch, s->cirrus_blt_srcpitch,
s->cirrus_blt_width, s->cirrus_blt_height);
@@ -801,8 +829,9 @@
} else {
/* at least one scan line */
do {
- (*s->cirrus_rop)(s, s->vram_ptr + s->cirrus_blt_dstaddr,
- s->cirrus_bltbuf, 0, 0, s->cirrus_blt_width, 1);
+ (*s->cirrus_rop)(s, s->vram_ptr +
+ (s->cirrus_blt_dstaddr & s->cirrus_addr_mask),
+ s->cirrus_bltbuf, 0, 0, s->cirrus_blt_width, 1);
cirrus_invalidate_region(s, s->cirrus_blt_dstaddr, 0,
s->cirrus_blt_width, 1);
s->cirrus_blt_dstaddr += s->cirrus_blt_dstpitch;
@@ -1920,7 +1949,7 @@
unsigned val = mem_value;
uint8_t *dst;
- dst = s->vram_ptr + offset;
+ dst = s->vram_ptr + (offset &= s->cirrus_addr_mask);
for (x = 0; x < 8; x++) {
if (val & 0x80) {
*dst = s->cirrus_shadow_gr1;
@@ -1943,7 +1972,7 @@
unsigned val = mem_value;
uint8_t *dst;
- dst = s->vram_ptr + offset;
+ dst = s->vram_ptr + (offset &= s->cirrus_addr_mask);
for (x = 0; x < 8; x++) {
if (val & 0x80) {
*dst = s->cirrus_shadow_gr1;
diff --git a/hw/cirrus_vga_rop.h b/hw/cirrus_vga_rop.h
index 3d6a1fe..0079d12 100644
--- a/hw/cirrus_vga_rop.h
+++ b/hw/cirrus_vga_rop.h
@@ -31,6 +31,12 @@
int x,y;
dstpitch -= bltwidth;
srcpitch -= bltwidth;
+
+ if (dstpitch < 0 || srcpitch < 0) {
+ /* is 0 valid? srcpitch == 0 could be useful */
+ return;
+ }
+
for (y = 0; y < bltheight; y++) {
for (x = 0; x < bltwidth; x++) {
ROP_OP(*dst, *src);
