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SUSE:SLE-12-SP4:GA
xen.7317
CVE-2014-3615-qemut-sanity-check-vbe.patch
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File CVE-2014-3615-qemut-sanity-check-vbe.patch of Package xen.7317
References: bsc#978164 CVE-2016-3710 XSA-179 Subject: CVE-2014-3615: vbe: rework sanity checks From: Andrew Cooper andrew.cooper3@citrix.com Sun Feb 22 19:21:08 2015 +0000 Date: Fri Oct 16 16:52:06 2015 +0100: Git: 8a1e383df25477e21b48c67c93c3a4dde19f9e4f Backport of qemu-upstream: * c1b886c45dc70f247300f549dce9833f3fa2def5 Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> Index: xen-4.4.4-testing/tools/qemu-xen-traditional-dir-remote/hw/vga.c =================================================================== --- xen-4.4.4-testing.orig/tools/qemu-xen-traditional-dir-remote/hw/vga.c +++ xen-4.4.4-testing/tools/qemu-xen-traditional-dir-remote/hw/vga.c @@ -521,6 +521,93 @@ static void vga_ioport_write(void *opaqu } #ifdef CONFIG_BOCHS_VBE +/* + * Sanity check vbe register writes. + * + * As we don't have a way to signal errors to the guest in the bochs + * dispi interface we'll go adjust the registers to the closest valid + * value. + */ +static void vbe_fixup_regs(VGAState *s) +{ + uint16_t *r = s->vbe_regs; + uint32_t bits, linelength, maxy, offset; + + if (!(r[VBE_DISPI_INDEX_ENABLE] & VBE_DISPI_ENABLED)) { + /* vbe is turned off -- nothing to do */ + return; + } + + /* check depth */ + switch (r[VBE_DISPI_INDEX_BPP]) { + case 4: + case 8: + case 16: + case 24: + case 32: + bits = r[VBE_DISPI_INDEX_BPP]; + break; + case 15: + bits = 16; + break; + default: + bits = r[VBE_DISPI_INDEX_BPP] = 8; + break; + } + + /* check width */ + r[VBE_DISPI_INDEX_XRES] &= ~7u; + if (r[VBE_DISPI_INDEX_XRES] == 0) { + r[VBE_DISPI_INDEX_XRES] = 8; + } + if (r[VBE_DISPI_INDEX_XRES] > VBE_DISPI_MAX_XRES) { + r[VBE_DISPI_INDEX_XRES] = VBE_DISPI_MAX_XRES; + } + r[VBE_DISPI_INDEX_VIRT_WIDTH] &= ~7u; + if (r[VBE_DISPI_INDEX_VIRT_WIDTH] > VBE_DISPI_MAX_XRES) { + r[VBE_DISPI_INDEX_VIRT_WIDTH] = VBE_DISPI_MAX_XRES; + } + if (r[VBE_DISPI_INDEX_VIRT_WIDTH] < r[VBE_DISPI_INDEX_XRES]) { + r[VBE_DISPI_INDEX_VIRT_WIDTH] = r[VBE_DISPI_INDEX_XRES]; + } + + /* check height */ + linelength = r[VBE_DISPI_INDEX_VIRT_WIDTH] * bits / 8; + maxy = s->vram_size / linelength; + if (r[VBE_DISPI_INDEX_YRES] == 0) { + r[VBE_DISPI_INDEX_YRES] = 1; + } + if (r[VBE_DISPI_INDEX_YRES] > VBE_DISPI_MAX_YRES) { + r[VBE_DISPI_INDEX_YRES] = VBE_DISPI_MAX_YRES; + } + if (r[VBE_DISPI_INDEX_YRES] > maxy) { + r[VBE_DISPI_INDEX_YRES] = maxy; + } + + /* check offset */ + if (r[VBE_DISPI_INDEX_X_OFFSET] > VBE_DISPI_MAX_XRES) { + r[VBE_DISPI_INDEX_X_OFFSET] = VBE_DISPI_MAX_XRES; + } + if (r[VBE_DISPI_INDEX_Y_OFFSET] > VBE_DISPI_MAX_YRES) { + r[VBE_DISPI_INDEX_Y_OFFSET] = VBE_DISPI_MAX_YRES; + } + offset = r[VBE_DISPI_INDEX_X_OFFSET] * bits / 8; + offset += r[VBE_DISPI_INDEX_Y_OFFSET] * linelength; + if (offset + r[VBE_DISPI_INDEX_YRES] * linelength > s->vram_size) { + r[VBE_DISPI_INDEX_Y_OFFSET] = 0; + offset = r[VBE_DISPI_INDEX_X_OFFSET] * bits / 8; + if (offset + r[VBE_DISPI_INDEX_YRES] * linelength > s->vram_size) { + r[VBE_DISPI_INDEX_X_OFFSET] = 0; + offset = 0; + } + } + + /* update vga state */ + r[VBE_DISPI_INDEX_VIRT_HEIGHT] = maxy; + s->vbe_line_offset = linelength; + s->vbe_start_addr = offset / 4; +} + static uint32_t vbe_ioport_read_index(void *opaque, uint32_t addr) { VGAState *s = opaque; @@ -588,22 +675,13 @@ static void vbe_ioport_write_data(void * } break; case VBE_DISPI_INDEX_XRES: - if ((val <= VBE_DISPI_MAX_XRES) && ((val & 7) == 0)) { - s->vbe_regs[s->vbe_index] = val; - } - break; case VBE_DISPI_INDEX_YRES: - if (val <= VBE_DISPI_MAX_YRES) { - s->vbe_regs[s->vbe_index] = val; - } - break; case VBE_DISPI_INDEX_BPP: - if (val == 0) - val = 8; - if (val == 4 || val == 8 || val == 15 || - val == 16 || val == 24 || val == 32) { - s->vbe_regs[s->vbe_index] = val; - } + case VBE_DISPI_INDEX_VIRT_WIDTH: + case VBE_DISPI_INDEX_X_OFFSET: + case VBE_DISPI_INDEX_Y_OFFSET: + s->vbe_regs[s->vbe_index] = val; + vbe_fixup_regs(s); break; case VBE_DISPI_INDEX_BANK: if (s->vbe_regs[VBE_DISPI_INDEX_BPP] == 4) { @@ -623,19 +701,11 @@ static void vbe_ioport_write_data(void * set_vram_mapping(s, s->lfb_addr, s->lfb_end); } - s->vbe_regs[VBE_DISPI_INDEX_VIRT_WIDTH] = - s->vbe_regs[VBE_DISPI_INDEX_XRES]; - s->vbe_regs[VBE_DISPI_INDEX_VIRT_HEIGHT] = - s->vbe_regs[VBE_DISPI_INDEX_YRES]; + s->vbe_regs[VBE_DISPI_INDEX_VIRT_WIDTH] = 0; s->vbe_regs[VBE_DISPI_INDEX_X_OFFSET] = 0; s->vbe_regs[VBE_DISPI_INDEX_Y_OFFSET] = 0; - - if (s->vbe_regs[VBE_DISPI_INDEX_BPP] == 4) - s->vbe_line_offset = s->vbe_regs[VBE_DISPI_INDEX_XRES] >> 1; - else - s->vbe_line_offset = s->vbe_regs[VBE_DISPI_INDEX_XRES] * - ((s->vbe_regs[VBE_DISPI_INDEX_BPP] + 7) >> 3); - s->vbe_start_addr = 0; + s->vbe_regs[VBE_DISPI_INDEX_ENABLE] |= VBE_DISPI_ENABLED; + vbe_fixup_regs(s); /* clear the screen (should be done in BIOS) */ if (!(val & VBE_DISPI_NOCLEARMEM)) { @@ -677,40 +747,6 @@ static void vbe_ioport_write_data(void * s->dac_8bit = (val & VBE_DISPI_8BIT_DAC) > 0; s->vbe_regs[s->vbe_index] = val; break; - case VBE_DISPI_INDEX_VIRT_WIDTH: - { - int w, h, line_offset; - - if (val < s->vbe_regs[VBE_DISPI_INDEX_XRES]) - return; - w = val; - if (s->vbe_regs[VBE_DISPI_INDEX_BPP] == 4) - line_offset = w >> 1; - else - line_offset = w * ((s->vbe_regs[VBE_DISPI_INDEX_BPP] + 7) >> 3); - h = s->vram_size / line_offset; - /* XXX: support weird bochs semantics ? */ - if (h < s->vbe_regs[VBE_DISPI_INDEX_YRES]) - return; - s->vbe_regs[VBE_DISPI_INDEX_VIRT_WIDTH] = w; - s->vbe_regs[VBE_DISPI_INDEX_VIRT_HEIGHT] = h; - s->vbe_line_offset = line_offset; - } - break; - case VBE_DISPI_INDEX_X_OFFSET: - case VBE_DISPI_INDEX_Y_OFFSET: - { - int x; - s->vbe_regs[s->vbe_index] = val; - s->vbe_start_addr = s->vbe_line_offset * s->vbe_regs[VBE_DISPI_INDEX_Y_OFFSET]; - x = s->vbe_regs[VBE_DISPI_INDEX_X_OFFSET]; - if (s->vbe_regs[VBE_DISPI_INDEX_BPP] == 4) - s->vbe_start_addr += x >> 1; - else - s->vbe_start_addr += x * ((s->vbe_regs[VBE_DISPI_INDEX_BPP] + 7) >> 3); - s->vbe_start_addr >>= 2; - } - break; default: break; }
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