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xen.10697
CVE-2017-13672-qemuu-vga-OOB-read-access-during...
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File CVE-2017-13672-qemuu-vga-OOB-read-access-during-display-update.patch of Package xen.10697
Subject: vga: stop passing pointers to vga_draw_line* functions From: Gerd Hoffmann kraxel@redhat.com Mon Aug 28 14:29:06 2017 +0200 Date: Fri Sep 1 13:52:43 2017 +0200: Git: 3d90c6254863693a6b13d918d2b8682e08bbc681 Instead pass around the address (aka offset into vga memory). Add vga_read_* helper functions which apply vbe_size_mask to the address, to make sure the address stays within the valid range, similar to the cirrus blitter fixes (commits ffaf857778 and 026aeffcb4). Impact: DoS for privileged guest users. qemu crashes with a segfault, when hitting the guard page after vga memory allocation, while reading vga memory for display updates. Fixes: CVE-2017-13672 Cc: P J P <ppandit@redhat.com> Reported-by: David Buchanan <d@vidbuchanan.co.uk> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com> Message-id: 20170828122906.18993-1-kraxel@redhat.com Index: xen-4.4.4-testing/tools/qemu-xen-dir-remote/hw/display/vga_template.h =================================================================== --- xen-4.4.4-testing.orig/tools/qemu-xen-dir-remote/hw/display/vga_template.h +++ xen-4.4.4-testing/tools/qemu-xen-dir-remote/hw/display/vga_template.h @@ -154,17 +154,17 @@ static void glue(vga_draw_glyph9_, DEPTH /* * 4 color mode */ -static void glue(vga_draw_line2_, DEPTH)(VGACommonState *s1, uint8_t *d, - const uint8_t *s, int width) +static void glue(vga_draw_line2_, DEPTH)(VGACommonState *vga, uint8_t *d, + uint32_t addr, int width) { uint32_t plane_mask, *palette, data, v; int x; - palette = s1->last_palette; - plane_mask = mask16[s1->ar[VGA_ATC_PLANE_ENABLE] & 0xf]; + palette = vga->last_palette; + plane_mask = mask16[vga->ar[VGA_ATC_PLANE_ENABLE] & 0xf]; width >>= 3; for(x = 0; x < width; x++) { - data = ((uint32_t *)s)[0]; + data = vga_read_dword_le(vga, addr); data &= plane_mask; v = expand2[GET_PLANE(data, 0)]; v |= expand2[GET_PLANE(data, 2)] << 2; @@ -180,7 +180,7 @@ static void glue(vga_draw_line2_, DEPTH) ((PIXEL_TYPE *)d)[6] = palette[(v >> 4) & 0xf]; ((PIXEL_TYPE *)d)[7] = palette[(v >> 0) & 0xf]; d += BPP * 8; - s += 4; + addr += 4; } } @@ -196,17 +196,17 @@ static void glue(vga_draw_line2_, DEPTH) /* * 4 color mode, dup2 horizontal */ -static void glue(vga_draw_line2d2_, DEPTH)(VGACommonState *s1, uint8_t *d, - const uint8_t *s, int width) +static void glue(vga_draw_line2d2_, DEPTH)(VGACommonState *vga, uint8_t *d, + uint32_t addr, int width) { uint32_t plane_mask, *palette, data, v; int x; - palette = s1->last_palette; - plane_mask = mask16[s1->ar[VGA_ATC_PLANE_ENABLE] & 0xf]; + palette = vga->last_palette; + plane_mask = mask16[vga->ar[VGA_ATC_PLANE_ENABLE] & 0xf]; width >>= 3; for(x = 0; x < width; x++) { - data = ((uint32_t *)s)[0]; + data = vga_read_dword_le(vga, addr); data &= plane_mask; v = expand2[GET_PLANE(data, 0)]; v |= expand2[GET_PLANE(data, 2)] << 2; @@ -222,24 +222,24 @@ static void glue(vga_draw_line2d2_, DEPT PUT_PIXEL2(d, 6, palette[(v >> 4) & 0xf]); PUT_PIXEL2(d, 7, palette[(v >> 0) & 0xf]); d += BPP * 16; - s += 4; + addr += 4; } } /* * 16 color mode */ -static void glue(vga_draw_line4_, DEPTH)(VGACommonState *s1, uint8_t *d, - const uint8_t *s, int width) +static void glue(vga_draw_line4_, DEPTH)(VGACommonState *vga, uint8_t *d, + uint32_t addr, int width) { uint32_t plane_mask, data, v, *palette; int x; - palette = s1->last_palette; - plane_mask = mask16[s1->ar[VGA_ATC_PLANE_ENABLE] & 0xf]; + palette = vga->last_palette; + plane_mask = mask16[vga->ar[VGA_ATC_PLANE_ENABLE] & 0xf]; width >>= 3; for(x = 0; x < width; x++) { - data = ((uint32_t *)s)[0]; + data = vga_read_dword_le(vga, addr); data &= plane_mask; v = expand4[GET_PLANE(data, 0)]; v |= expand4[GET_PLANE(data, 1)] << 1; @@ -254,24 +254,24 @@ static void glue(vga_draw_line4_, DEPTH) ((PIXEL_TYPE *)d)[6] = palette[(v >> 4) & 0xf]; ((PIXEL_TYPE *)d)[7] = palette[(v >> 0) & 0xf]; d += BPP * 8; - s += 4; + addr += 4; } } /* * 16 color mode, dup2 horizontal */ -static void glue(vga_draw_line4d2_, DEPTH)(VGACommonState *s1, uint8_t *d, - const uint8_t *s, int width) +static void glue(vga_draw_line4d2_, DEPTH)(VGACommonState *vga, uint8_t *d, + uint32_t addr, int width) { uint32_t plane_mask, data, v, *palette; int x; - palette = s1->last_palette; - plane_mask = mask16[s1->ar[VGA_ATC_PLANE_ENABLE] & 0xf]; + palette = vga->last_palette; + plane_mask = mask16[vga->ar[VGA_ATC_PLANE_ENABLE] & 0xf]; width >>= 3; for(x = 0; x < width; x++) { - data = ((uint32_t *)s)[0]; + data = vga_read_dword_le(vga, addr); data &= plane_mask; v = expand4[GET_PLANE(data, 0)]; v |= expand4[GET_PLANE(data, 1)] << 1; @@ -286,7 +286,7 @@ static void glue(vga_draw_line4d2_, DEPT PUT_PIXEL2(d, 6, palette[(v >> 4) & 0xf]); PUT_PIXEL2(d, 7, palette[(v >> 0) & 0xf]); d += BPP * 16; - s += 4; + addr += 4; } } @@ -295,21 +295,21 @@ static void glue(vga_draw_line4d2_, DEPT * * XXX: add plane_mask support (never used in standard VGA modes) */ -static void glue(vga_draw_line8d2_, DEPTH)(VGACommonState *s1, uint8_t *d, - const uint8_t *s, int width) +static void glue(vga_draw_line8d2_, DEPTH)(VGACommonState *vga, uint8_t *d, + uint32_t addr, int width) { uint32_t *palette; int x; - palette = s1->last_palette; + palette = vga->last_palette; width >>= 3; for(x = 0; x < width; x++) { - PUT_PIXEL2(d, 0, palette[s[0]]); - PUT_PIXEL2(d, 1, palette[s[1]]); - PUT_PIXEL2(d, 2, palette[s[2]]); - PUT_PIXEL2(d, 3, palette[s[3]]); + PUT_PIXEL2(d, 0, palette[vga_read_byte(vga, addr + 0)]); + PUT_PIXEL2(d, 1, palette[vga_read_byte(vga, addr + 1)]); + PUT_PIXEL2(d, 2, palette[vga_read_byte(vga, addr + 2)]); + PUT_PIXEL2(d, 3, palette[vga_read_byte(vga, addr + 3)]); d += BPP * 8; - s += 4; + addr += 4; } } @@ -318,25 +318,25 @@ static void glue(vga_draw_line8d2_, DEPT * * XXX: add plane_mask support (never used in standard VGA modes) */ -static void glue(vga_draw_line8_, DEPTH)(VGACommonState *s1, uint8_t *d, - const uint8_t *s, int width) +static void glue(vga_draw_line8_, DEPTH)(VGACommonState *vga, uint8_t *d, + uint32_t addr, int width) { uint32_t *palette; int x; - palette = s1->last_palette; + palette = vga->last_palette; width >>= 3; for(x = 0; x < width; x++) { - ((PIXEL_TYPE *)d)[0] = palette[s[0]]; - ((PIXEL_TYPE *)d)[1] = palette[s[1]]; - ((PIXEL_TYPE *)d)[2] = palette[s[2]]; - ((PIXEL_TYPE *)d)[3] = palette[s[3]]; - ((PIXEL_TYPE *)d)[4] = palette[s[4]]; - ((PIXEL_TYPE *)d)[5] = palette[s[5]]; - ((PIXEL_TYPE *)d)[6] = palette[s[6]]; - ((PIXEL_TYPE *)d)[7] = palette[s[7]]; + ((uint32_t *)d)[0] = palette[vga_read_byte(vga, addr + 0)]; + ((uint32_t *)d)[1] = palette[vga_read_byte(vga, addr + 1)]; + ((uint32_t *)d)[2] = palette[vga_read_byte(vga, addr + 2)]; + ((uint32_t *)d)[3] = palette[vga_read_byte(vga, addr + 3)]; + ((uint32_t *)d)[4] = palette[vga_read_byte(vga, addr + 4)]; + ((uint32_t *)d)[5] = palette[vga_read_byte(vga, addr + 5)]; + ((uint32_t *)d)[6] = palette[vga_read_byte(vga, addr + 6)]; + ((uint32_t *)d)[7] = palette[vga_read_byte(vga, addr + 7)]; d += BPP * 8; - s += 8; + addr += 8; } } @@ -348,23 +348,23 @@ static void glue(vga_draw_line8_, DEPTH) /* * 15 bit color */ -static void glue(vga_draw_line15_, PIXEL_NAME)(VGACommonState *s1, uint8_t *d, - const uint8_t *s, int width) +static void glue(vga_draw_line15_, PIXEL_NAME)(VGACommonState *vga, uint8_t *d, + uint32_t addr, int width) { #if DEPTH == 15 && defined(HOST_WORDS_BIGENDIAN) == defined(TARGET_WORDS_BIGENDIAN) - memcpy(d, s, width * 2); + memcpy(d, (uint8_t *)addr, width * 2); #else int w; uint32_t v, r, g, b; w = width; do { - v = lduw_raw((void *)s); + v = vga_read_word_le(vga, addr); r = (v >> 7) & 0xf8; g = (v >> 2) & 0xf8; b = (v << 3) & 0xf8; ((PIXEL_TYPE *)d)[0] = glue(rgb_to_pixel, PIXEL_NAME)(r, g, b); - s += 2; + addr += 2; d += BPP; } while (--w != 0); #endif @@ -373,23 +373,23 @@ static void glue(vga_draw_line15_, PIXEL /* * 16 bit color */ -static void glue(vga_draw_line16_, PIXEL_NAME)(VGACommonState *s1, uint8_t *d, - const uint8_t *s, int width) +static void glue(vga_draw_line16_, PIXEL_NAME)(VGACommonState *vga, uint8_t *d, + uint32_t addr, int width) { #if DEPTH == 16 && defined(HOST_WORDS_BIGENDIAN) == defined(TARGET_WORDS_BIGENDIAN) - memcpy(d, s, width * 2); + memcpy(d, (uint8_t *)addr, width * 2); #else int w; uint32_t v, r, g, b; w = width; do { - v = lduw_raw((void *)s); + v = vga_read_word_le(vga, addr); r = (v >> 8) & 0xf8; g = (v >> 3) & 0xfc; b = (v << 3) & 0xf8; ((PIXEL_TYPE *)d)[0] = glue(rgb_to_pixel, PIXEL_NAME)(r, g, b); - s += 2; + addr += 2; d += BPP; } while (--w != 0); #endif @@ -398,8 +398,8 @@ static void glue(vga_draw_line16_, PIXEL /* * 24 bit color */ -static void glue(vga_draw_line24_, PIXEL_NAME)(VGACommonState *s1, uint8_t *d, - const uint8_t *s, int width) +static void glue(vga_draw_line24_, PIXEL_NAME)(VGACommonState *vga, uint8_t *d, + uint32_t addr, int width) { int w; uint32_t r, g, b; @@ -407,16 +407,16 @@ static void glue(vga_draw_line24_, PIXEL w = width; do { #if defined(TARGET_WORDS_BIGENDIAN) - r = s[0]; - g = s[1]; - b = s[2]; + r = vga_read_byte(vga, addr + 0); + g = vga_read_byte(vga, addr + 1); + b = vga_read_byte(vga, addr + 2); #else - b = s[0]; - g = s[1]; - r = s[2]; + b = vga_read_byte(vga, addr + 0); + g = vga_read_byte(vga, addr + 1); + r = vga_read_byte(vga, addr + 2); #endif ((PIXEL_TYPE *)d)[0] = glue(rgb_to_pixel, PIXEL_NAME)(r, g, b); - s += 3; + addr += 3; d += BPP; } while (--w != 0); } @@ -424,11 +424,11 @@ static void glue(vga_draw_line24_, PIXEL /* * 32 bit color */ -static void glue(vga_draw_line32_, PIXEL_NAME)(VGACommonState *s1, uint8_t *d, - const uint8_t *s, int width) +static void glue(vga_draw_line32_, PIXEL_NAME)(VGACommonState *vga, uint8_t *d, + uint32_t addr, int width) { #if DEPTH == 32 && defined(HOST_WORDS_BIGENDIAN) == defined(TARGET_WORDS_BIGENDIAN) && !defined(BGR_FORMAT) - memcpy(d, s, width * 4); + memcpy(d, (uint8_t *)addr, width * 4); #else int w; uint32_t r, g, b; @@ -436,16 +436,16 @@ static void glue(vga_draw_line32_, PIXEL w = width; do { #if defined(TARGET_WORDS_BIGENDIAN) - r = s[1]; - g = s[2]; - b = s[3]; + r = vga_read_byte(vga, addr + 0); + g = vga_read_byte(vga, addr + 1); + b = vga_read_byte(vga, addr + 2); #else - b = s[0]; - g = s[1]; - r = s[2]; + b = vga_read_byte(vga, addr + 0); + g = vga_read_byte(vga, addr + 1); + r = vga_read_byte(vga, addr + 2); #endif ((PIXEL_TYPE *)d)[0] = glue(rgb_to_pixel, PIXEL_NAME)(r, g, b); - s += 4; + addr += 4; d += BPP; } while (--w != 0); #endif Index: xen-4.4.4-testing/tools/qemu-xen-dir-remote/hw/display/vga.c =================================================================== --- xen-4.4.4-testing.orig/tools/qemu-xen-dir-remote/hw/display/vga.c +++ xen-4.4.4-testing/tools/qemu-xen-dir-remote/hw/display/vga.c @@ -1054,7 +1054,33 @@ typedef void vga_draw_glyph9_func(uint8_ const uint8_t *font_ptr, int h, uint32_t fgcol, uint32_t bgcol, int dup9); typedef void vga_draw_line_func(VGACommonState *s1, uint8_t *d, - const uint8_t *s, int width); + uint32_t srcaddr, int width); + +static inline uint8_t vga_read_byte(VGACommonState *vga, uint32_t addr) +{ + return vga->vram_ptr[addr & vga->vbe_size_mask]; +} + +static inline uint16_t vga_read_word_le(VGACommonState *vga, uint32_t addr) +{ + uint32_t offset = addr & vga->vbe_size_mask & ~1; + uint16_t *ptr = (uint16_t *)(vga->vram_ptr + offset); + return lduw_le_p(ptr); +} + +static inline uint16_t vga_read_word_be(VGACommonState *vga, uint32_t addr) +{ + uint32_t offset = addr & vga->vbe_size_mask & ~1; + uint16_t *ptr = (uint16_t *)(vga->vram_ptr + offset); + return lduw_be_p(ptr); +} + +static inline uint32_t vga_read_dword_le(VGACommonState *vga, uint32_t addr) +{ + uint32_t offset = addr & vga->vbe_size_mask & ~3; + uint32_t *ptr = (uint32_t *)(vga->vram_ptr + offset); + return ldl_le_p(ptr); +} #define DEPTH 8 #include "vga_template.h" @@ -1888,7 +1914,7 @@ static void vga_draw_graphic(VGACommonSt if (page1 > page_max) page_max = page1; if (!(is_buffer_shared(surface))) { - vga_draw_line(s, d, s->vram_ptr + addr, width); + vga_draw_line(s, d, addr, width); if (s->cursor_draw_line) s->cursor_draw_line(s, d, y); } @@ -2358,6 +2384,7 @@ void vga_common_init(VGACommonState *s, } expand4to8[i] = v; } + s->vbe_size_mask = s->vbe_size - 1; /* valid range: 1 MB -> 256 MB */ s->vram_size = 1024 * 1024; Index: xen-4.4.4-testing/tools/qemu-xen-dir-remote/hw/display/vga_int.h =================================================================== --- xen-4.4.4-testing.orig/tools/qemu-xen-dir-remote/hw/display/vga_int.h +++ xen-4.4.4-testing/tools/qemu-xen-dir-remote/hw/display/vga_int.h @@ -94,6 +94,7 @@ typedef struct VGACommonState { uint32_t vram_size; uint32_t vram_size_mb; /* property */ uint32_t vbe_size; + uint32_t vbe_size_mask; uint32_t latch; MemoryRegion *chain4_alias; uint8_t sr_index;
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