From 6febc393af5d81e2c3f6f0d2f0e5b7dd58d4974a Mon Sep 17 00:00:00 2001 From: Gerd Hoffmann Date: Wed, 3 Dec 2014 09:17:55 +0100 Subject: [PATCH 2/3] cirrus: fix blit region check RH-Author: Gerd Hoffmann Message-id: <1417594676-5663-2-git-send-email-kraxel@redhat.com> O-Subject: [RHEL-7.1 qemu-kvm PATCH 1/2] cirrus: fix blit region check Bugzilla: 1169456 RH-Acked-by: Paolo Bonzini RH-Acked-by: Laszlo Ersek RH-Acked-by: Dr. David Alan Gilbert Issues: * Doesn't check pitches correctly in case it is negative. * Doesn't check width at all. Turn macro into functions while being at it, also factor out the check for one region which we then can simply call twice for src + dst. This is CVE-2014-8106. Reported-by: Paolo Bonzini Signed-off-by: Gerd Hoffmann Reviewed-by: Paolo Bonzini (cherry picked from commit d3532a0db02296e687711b8cdc7791924efccea0) --- hw/display/cirrus_vga.c | 61 +++++++++++++++++++++++++++++++++++-------------- 1 file changed, 44 insertions(+), 17 deletions(-) diff --git a/hw/display/cirrus_vga.c b/hw/display/cirrus_vga.c index bfaa0b0..9ae8313 100644 --- a/hw/display/cirrus_vga.c +++ b/hw/display/cirrus_vga.c @@ -172,20 +172,6 @@ #define CIRRUS_PNPMMIO_SIZE 0x1000 -#define BLTUNSAFE(s) \ - ( \ - ( /* check dst is within bounds */ \ - (s)->cirrus_blt_height * ABS((s)->cirrus_blt_dstpitch) \ - + ((s)->cirrus_blt_dstaddr & (s)->cirrus_addr_mask) > \ - (s)->vga.vram_size \ - ) || \ - ( /* check src is within bounds */ \ - (s)->cirrus_blt_height * ABS((s)->cirrus_blt_srcpitch) \ - + ((s)->cirrus_blt_srcaddr & (s)->cirrus_addr_mask) > \ - (s)->vga.vram_size \ - ) \ - ) - struct CirrusVGAState; typedef void (*cirrus_bitblt_rop_t) (struct CirrusVGAState *s, uint8_t * dst, const uint8_t * src, @@ -278,6 +264,46 @@ static void cirrus_update_memory_access(CirrusVGAState *s); * ***************************************/ +static bool blit_region_is_unsafe(struct CirrusVGAState *s, + int32_t pitch, int32_t addr) +{ + 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) { + return true; + } + } else { + int64_t max = addr + + ((int64_t)s->cirrus_blt_height-1) * pitch + + s->cirrus_blt_width; + if (max >= s->vga.vram_size) { + return true; + } + } + return false; +} + +static bool blit_is_unsafe(struct CirrusVGAState *s) +{ + /* should be the case, see cirrus_bitblt_start */ + assert(s->cirrus_blt_width > 0); + assert(s->cirrus_blt_height > 0); + + if (blit_region_is_unsafe(s, s->cirrus_blt_dstpitch, + s->cirrus_blt_dstaddr & s->cirrus_addr_mask)) { + return true; + } + if (blit_region_is_unsafe(s, s->cirrus_blt_srcpitch, + s->cirrus_blt_srcaddr & s->cirrus_addr_mask)) { + return true; + } + + return false; +} + static void cirrus_bitblt_rop_nop(CirrusVGAState *s, uint8_t *dst,const uint8_t *src, int dstpitch,int srcpitch, @@ -635,7 +661,7 @@ static int cirrus_bitblt_common_patterncopy(CirrusVGAState * s, dst = s->vga.vram_ptr + (s->cirrus_blt_dstaddr & s->cirrus_addr_mask); - if (BLTUNSAFE(s)) + if (blit_is_unsafe(s)) return 0; (*s->cirrus_rop) (s, dst, src, @@ -653,8 +679,9 @@ static int cirrus_bitblt_solidfill(CirrusVGAState *s, int blt_rop) { cirrus_fill_t rop_func; - if (BLTUNSAFE(s)) + if (blit_is_unsafe(s)) { return 0; + } rop_func = cirrus_fill[rop_to_index[blt_rop]][s->cirrus_blt_pixelwidth - 1]; rop_func(s, s->vga.vram_ptr + (s->cirrus_blt_dstaddr & s->cirrus_addr_mask), s->cirrus_blt_dstpitch, @@ -751,7 +778,7 @@ static void cirrus_do_copy(CirrusVGAState *s, int dst, int src, int w, int h) static int cirrus_bitblt_videotovideo_copy(CirrusVGAState * s) { - if (BLTUNSAFE(s)) + if (blit_is_unsafe(s)) return 0; cirrus_do_copy(s, s->cirrus_blt_dstaddr - s->vga.start_addr, -- 1.8.3.1