From 6febc393af5d81e2c3f6f0d2f0e5b7dd58d4974a Mon Sep 17 00:00:00 2001

From: Gerd Hoffmann <kraxel@redhat.com>

Date: Wed, 3 Dec 2014 09:17:55 +0100

Subject: [PATCH 2/3] cirrus: fix blit region check

RH-Author: Gerd Hoffmann <kraxel@redhat.com>

Message-id: <1417594676-5663-2-git-send-email-kraxel@redhat.com>

O-Subject: [RHEL-7.1 qemu-kvm PATCH 1/2] cirrus: fix blit region check

Bugzilla: 1169456

RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>

RH-Acked-by: Laszlo Ersek <lersek@redhat.com>

RH-Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

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>

(cherry picked from commit d3532a0db02296e687711b8cdc7791924efccea0)

---

 hw/display/cirrus_vga.c | 61 +++++++++++++++++++++++++++++++++++--------------

 1 file changed, 44 insertions(+), 17 deletions(-)

diff --git a/hw/display/cirrus_vga.c b/hw/display/cirrus_vga.c

index bfaa0b0..9ae8313 100644

--- a/hw/display/cirrus_vga.c

+++ b/hw/display/cirrus_vga.c

@@ -172,20 +172,6 @@

 #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,

@@ -278,6 +264,46 @@ 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,

@@ -635,7 +661,7 @@ 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,

@@ -653,8 +679,9 @@ 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,

@@ -751,7 +778,7 @@ 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,

-- 

1.8.3.1