From 6420a8c59712cce74ad689c0d692982665a785b0 Mon Sep 17 00:00:00 2001 From: Gerd Hoffmann Date: Fri, 20 Oct 2017 11:06:19 +0200 Subject: [PATCH 4/7] cirrus: fix oob access in mode4and5 write functions RH-Author: Gerd Hoffmann Message-id: <20171020110619.2541-12-kraxel@redhat.com> Patchwork-id: 77403 O-Subject: [RHEL-7.5 qemu-kvm PATCH 11/11] cirrus: fix oob access in mode4and5 write functions Bugzilla: 1501295 RH-Acked-by: Stefan Hajnoczi RH-Acked-by: Dr. David Alan Gilbert RH-Acked-by: Miroslav Rezanina Move dst calculation into the loop, so we apply the mask on each interation and will not overflow vga memory. Cc: Prasad J Pandit Reported-by: Niu Guoxiang Signed-off-by: Gerd Hoffmann Message-id: 20171011084314.21752-1-kraxel@redhat.com (cherry picked from commit eb38e1bc3740725ca29a535351de94107ec58d51) Signed-off-by: Miroslav Rezanina --- hw/display/cirrus_vga.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/hw/display/cirrus_vga.c b/hw/display/cirrus_vga.c index c1324ab..a07fa9c 100644 --- a/hw/display/cirrus_vga.c +++ b/hw/display/cirrus_vga.c @@ -2023,15 +2023,14 @@ static void cirrus_mem_writeb_mode4and5_8bpp(CirrusVGAState * s, unsigned val = mem_value; uint8_t *dst; - dst = s->vga.vram_ptr + (offset &= s->cirrus_addr_mask); for (x = 0; x < 8; x++) { + dst = s->vga.vram_ptr + ((offset + x) & s->cirrus_addr_mask); if (val & 0x80) { *dst = s->cirrus_shadow_gr1; } else if (mode == 5) { *dst = s->cirrus_shadow_gr0; } val <<= 1; - dst++; } memory_region_set_dirty(&s->vga.vram, offset, 8); } @@ -2045,8 +2044,8 @@ static void cirrus_mem_writeb_mode4and5_16bpp(CirrusVGAState * s, unsigned val = mem_value; uint8_t *dst; - dst = s->vga.vram_ptr + (offset &= s->cirrus_addr_mask); for (x = 0; x < 8; x++) { + dst = s->vga.vram_ptr + ((offset + 2 * x) & s->cirrus_addr_mask & ~1); if (val & 0x80) { *dst = s->cirrus_shadow_gr1; *(dst + 1) = s->vga.gr[0x11]; @@ -2055,7 +2054,6 @@ static void cirrus_mem_writeb_mode4and5_16bpp(CirrusVGAState * s, *(dst + 1) = s->vga.gr[0x10]; } val <<= 1; - dst += 2; } memory_region_set_dirty(&s->vga.vram, offset, 16); } -- 1.8.3.1