[Qemu-devel] [PATCH] fix :cirrus_vga fix OOB read case qemu Segmentation fault

[hangaohuai]

check the validity of parameters in cirrus_bitblt_rop_fwd_transp_xxx
and cirrus_bitblt_rop_fwd_xxx to avoid the OOB read which causes qemu 
Segmentation fault.

After the fix, we will touch the assert in
cirrus_invalidate_region:
assert(off_cur_end >= off_cur);

Signed-off-by: fangying <address@hidden>
Signed-off-by: hangaohuai <address@hidden>
---
 hw/display/cirrus_vga_rop.h | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/hw/display/cirrus_vga_rop.h b/hw/display/cirrus_vga_rop.h
index 0925a00..12a15e0 100644
--- a/hw/display/cirrus_vga_rop.h
+++ b/hw/display/cirrus_vga_rop.h
@@ -97,6 +97,11 @@ glue(glue(cirrus_bitblt_rop_fwd_transp_, 
ROP_NAME),_8)(CirrusVGAState *s,
     uint8_t p;
     dstpitch -= bltwidth;
     srcpitch -= bltwidth;
+
+    if (dstpitch < 0 || srcpitch < 0) {
+        return;
+    }
+
     for (y = 0; y < bltheight; y++) {
         for (x = 0; x < bltwidth; x++) {
            p = *dst;
@@ -143,6 +148,11 @@ glue(glue(cirrus_bitblt_rop_fwd_transp_, 
ROP_NAME),_16)(CirrusVGAState *s,
     uint8_t p1, p2;
     dstpitch -= bltwidth;
     srcpitch -= bltwidth;
+
+    if (srcpitch < 0 || dstpitch < 0) {
+        return;
+    }
+
     for (y = 0; y < bltheight; y++) {
         for (x = 0; x < bltwidth; x+=2) {
            p1 = *dst;
-- 
1.8.3.1