From 62d4c6bd5263bb8413a06c80144fc678df6dfb64 Mon Sep 17 00:00:00 2001 From: Li Qiang Date: Wed, 1 Feb 2017 09:35:01 +0100 Subject: [PATCH] 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: Li Qiang { 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 Message-id: 1485938101-26602-1-git-send-email-kraxel@redhat.com Reviewed-by: Laszlo Ersek --- 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 7db6409..16f27e8 100644 --- a/hw/display/cirrus_vga.c +++ b/hw/display/cirrus_vga.c @@ -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 { -- 2.10.2