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From d3532a0db02296e687711b8cdc7791924efccea0 Mon Sep 17 00:00:00 2001
From: Gerd Hoffmann <kraxel@redhat.com>
Date: Wed, 19 Nov 2014 11:37:42 +0100
Subject: cirrus: fix blit region check
Bug-Debian: http://bugs.debian.org/772025
Issues:
* Doesn't check pitches correctly in case it is negative.
* Doesn't check width at all.
Turn macro into functions while being at it, also factor out the check
for one region which we then can simply call twice for src + dst.
This is CVE-2014-8106.
Reported-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
(Backported to 1.1 by Michael Tokarev <mjt@tls.msk.ru>)
---
hw/cirrus_vga.c | 61 ++++++++++++++++++++++++++++++++++-------------
1 file changed, 44 insertions(+), 17 deletions(-)
diff --git a/hw/cirrus_vga.c b/hw/cirrus_vga.c
index 8a5b76c..d54fb06 100644
--- a/hw/cirrus_vga.c
+++ b/hw/cirrus_vga.c
@@ -173,20 +173,6 @@
#define CIRRUS_PNPMMIO_SIZE 0x1000
-#define BLTUNSAFE(s) \
- ( \
- ( /* check dst is within bounds */ \
- (s)->cirrus_blt_height * ABS((s)->cirrus_blt_dstpitch) \
- + ((s)->cirrus_blt_dstaddr & (s)->cirrus_addr_mask) > \
- (s)->vga.vram_size \
- ) || \
- ( /* check src is within bounds */ \
- (s)->cirrus_blt_height * ABS((s)->cirrus_blt_srcpitch) \
- + ((s)->cirrus_blt_srcaddr & (s)->cirrus_addr_mask) > \
- (s)->vga.vram_size \
- ) \
- )
-
struct CirrusVGAState;
typedef void (*cirrus_bitblt_rop_t) (struct CirrusVGAState *s,
uint8_t * dst, const uint8_t * src,
@@ -279,6 +265,46 @@ static void cirrus_update_memory_access(CirrusVGAState *s);
*
***************************************/
+static bool blit_region_is_unsafe(struct CirrusVGAState *s,
+ int32_t pitch, int32_t addr)
+{
+ if (pitch < 0) {
+ int64_t min = addr
+ + ((int64_t)s->cirrus_blt_height-1) * pitch;
+ int32_t max = addr
+ + s->cirrus_blt_width;
+ if (min < 0 || max >= s->vga.vram_size) {
+ return true;
+ }
+ } else {
+ int64_t max = addr
+ + ((int64_t)s->cirrus_blt_height-1) * pitch
+ + s->cirrus_blt_width;
+ if (max >= s->vga.vram_size) {
+ return true;
+ }
+ }
+ return false;
+}
+
+static bool blit_is_unsafe(struct CirrusVGAState *s)
+{
+ /* should be the case, see cirrus_bitblt_start */
+ assert(s->cirrus_blt_width > 0);
+ assert(s->cirrus_blt_height > 0);
+
+ if (blit_region_is_unsafe(s, s->cirrus_blt_dstpitch,
+ s->cirrus_blt_dstaddr & s->cirrus_addr_mask)) {
+ return true;
+ }
+ if (blit_region_is_unsafe(s, s->cirrus_blt_srcpitch,
+ s->cirrus_blt_srcaddr & s->cirrus_addr_mask)) {
+ return true;
+ }
+
+ return false;
+}
+
static void cirrus_bitblt_rop_nop(CirrusVGAState *s,
uint8_t *dst,const uint8_t *src,
int dstpitch,int srcpitch,
@@ -636,7 +662,7 @@ static int cirrus_bitblt_common_patterncopy(CirrusVGAState * s,
dst = s->vga.vram_ptr + (s->cirrus_blt_dstaddr & s->cirrus_addr_mask);
- if (BLTUNSAFE(s))
+ if (blit_is_unsafe(s))
return 0;
(*s->cirrus_rop) (s, dst, src,
@@ -654,8 +680,9 @@ static int cirrus_bitblt_solidfill(CirrusVGAState *s, int blt_rop)
{
cirrus_fill_t rop_func;
- if (BLTUNSAFE(s))
+ if (blit_is_unsafe(s)) {
return 0;
+ }
rop_func = cirrus_fill[rop_to_index[blt_rop]][s->cirrus_blt_pixelwidth - 1];
rop_func(s, s->vga.vram_ptr + (s->cirrus_blt_dstaddr & s->cirrus_addr_mask),
s->cirrus_blt_dstpitch,
@@ -752,7 +779,7 @@ static void cirrus_do_copy(CirrusVGAState *s, int dst, int src, int w, int h)
static int cirrus_bitblt_videotovideo_copy(CirrusVGAState * s)
{
- if (BLTUNSAFE(s))
+ if (blit_is_unsafe(s))
return 0;
cirrus_do_copy(s, s->cirrus_blt_dstaddr - s->vga.start_addr,
--
1.7.10.4
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