Commit 62d4c6bd authored by Li Qiang's avatar Li Qiang Committed by Gerd Hoffmann
Browse files

cirrus: fix oob access issue (CVE-2017-2615) 



When doing bitblt copy in backward mode, we should minus the
blt width first just like the adding in the forward mode. This
can avoid the oob access of the front of vga's vram.

Signed-off-by: default avatarLi Qiang <liqiang6-s@360.cn>

{ kraxel: with backward blits (negative pitch) addr is the topmost
          address, so check it as-is against vram size ]

Cc: qemu-stable@nongnu.org
Cc: P J P <ppandit@redhat.com>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Wolfgang Bumiller <w.bumiller@proxmox.com>
Fixes: d3532a0d (CVE-2014-8106)
Signed-off-by: default avatarGerd Hoffmann <kraxel@redhat.com>
Message-id: 1485938101-26602-1-git-send-email-kraxel@redhat.com
Reviewed-by: default avatarLaszlo Ersek <lersek@redhat.com>
parent 60cd23e8

hw/display/cirrus_vga.c

+3 −4
Original line number Diff line number Diff line
@@ -274,10 +274,9 @@ static bool blit_region_is_unsafe(struct CirrusVGAState *s, 
{

    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) {

            + ((int64_t)s->cirrus_blt_height - 1) * pitch

            - s->cirrus_blt_width;

        if (min < -1 || addr >= s->vga.vram_size) {

            return true;

        }

    } else {