From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:56973) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cWKWD-00085i-E4 for qemu-devel@nongnu.org; Wed, 25 Jan 2017 05:09:34 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cWKW9-0000jQ-Ci for qemu-devel@nongnu.org; Wed, 25 Jan 2017 05:09:33 -0500 From: Gerd Hoffmann Date: Wed, 25 Jan 2017 11:09:17 +0100 Message-Id: <1485338957-16939-1-git-send-email-kraxel@redhat.com> Subject: [Qemu-devel] [PATCH v2] cirrus: fix oob access issue (CVE-2017-TODO) List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Li Qiang , qemu-stable@nongnu.org, P J P , Laszlo Ersek , Paolo Bonzini , Wolfgang Bumiller , Gerd Hoffmann From: Li Qiang 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: Li Qiang Message-id: 5887254f.863a240a.2c122.5500@mx.google.com { 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 Cc: Laszlo Ersek Cc: Paolo Bonzini Cc: Wolfgang Bumiller Fixes: d3532a0db02296e687711b8cdc7791924efccea0 (CVE-2014-8106) Signed-off-by: Gerd Hoffmann --- hw/display/cirrus_vga.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/hw/display/cirrus_vga.c b/hw/display/cirrus_vga.c index 379910d..5547a60 100644 --- a/hw/display/cirrus_vga.c +++ b/hw/display/cirrus_vga.c @@ -277,10 +277,9 @@ 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 < 0 || addr >= s->vga.vram_size) { return true; } } else { -- 1.8.3.1