44adf367dc
Invalid font data passed to PIO_VFONT can result in an integer overflow in glyphsize. Characters may then be drawn on the console using glyph map entries that point beyond the end of allocated glyph memory, resulting in a kernel memory disclosure. Submitted by: emaste Reported by: Dr. Silvio Cesare of InfoSect Security: CVE-2018-6917 Security: FreeBSD-SA-18:04.vt Sponsored by: The FreeBSD Foundation
229 lines
5.9 KiB
C
229 lines
5.9 KiB
C
/*-
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* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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*
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* Copyright (c) 2009 The FreeBSD Foundation
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* All rights reserved.
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*
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* This software was developed by Ed Schouten under sponsorship from the
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* FreeBSD Foundation.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <sys/kernel.h>
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#include <sys/malloc.h>
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#include <sys/refcount.h>
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#include <sys/systm.h>
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#include <dev/vt/vt.h>
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static MALLOC_DEFINE(M_VTFONT, "vtfont", "vt font");
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/* Some limits to prevent abnormal fonts from being loaded. */
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#define VTFONT_MAXMAPPINGS 65536
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#define VTFONT_MAXGLYPHS 131072
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#define VTFONT_MAXGLYPHSIZE 2097152
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#define VTFONT_MAXDIMENSION 128
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static uint16_t
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vtfont_bisearch(const struct vt_font_map *map, unsigned int len, uint32_t src)
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{
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int min, mid, max;
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min = 0;
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max = len - 1;
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/* Empty font map. */
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if (len == 0)
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return (0);
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/* Character below minimal entry. */
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if (src < map[0].vfm_src)
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return (0);
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/* Optimization: ASCII characters occur very often. */
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if (src <= map[0].vfm_src + map[0].vfm_len)
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return (src - map[0].vfm_src + map[0].vfm_dst);
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/* Character above maximum entry. */
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if (src > map[max].vfm_src + map[max].vfm_len)
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return (0);
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/* Binary search. */
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while (max >= min) {
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mid = (min + max) / 2;
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if (src < map[mid].vfm_src)
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max = mid - 1;
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else if (src > map[mid].vfm_src + map[mid].vfm_len)
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min = mid + 1;
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else
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return (src - map[mid].vfm_src + map[mid].vfm_dst);
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}
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return (0);
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}
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const uint8_t *
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vtfont_lookup(const struct vt_font *vf, term_char_t c)
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{
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uint32_t src;
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uint16_t dst;
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size_t stride;
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unsigned int normal_map;
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unsigned int bold_map;
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/*
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* No support for printing right hand sides for CJK fullwidth
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* characters. Simply print a space and assume that the left
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* hand side describes the entire character.
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*/
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src = TCHAR_CHARACTER(c);
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if (TCHAR_FORMAT(c) & TF_CJK_RIGHT) {
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normal_map = VFNT_MAP_NORMAL_RIGHT;
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bold_map = VFNT_MAP_BOLD_RIGHT;
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} else {
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normal_map = VFNT_MAP_NORMAL;
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bold_map = VFNT_MAP_BOLD;
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}
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if (TCHAR_FORMAT(c) & TF_BOLD) {
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dst = vtfont_bisearch(vf->vf_map[bold_map],
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vf->vf_map_count[bold_map], src);
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if (dst != 0)
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goto found;
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}
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dst = vtfont_bisearch(vf->vf_map[normal_map],
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vf->vf_map_count[normal_map], src);
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found:
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stride = howmany(vf->vf_width, 8) * vf->vf_height;
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return (&vf->vf_bytes[dst * stride]);
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}
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struct vt_font *
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vtfont_ref(struct vt_font *vf)
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{
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refcount_acquire(&vf->vf_refcount);
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return (vf);
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}
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void
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vtfont_unref(struct vt_font *vf)
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{
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unsigned int i;
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if (refcount_release(&vf->vf_refcount)) {
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for (i = 0; i < VFNT_MAPS; i++)
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free(vf->vf_map[i], M_VTFONT);
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free(vf->vf_bytes, M_VTFONT);
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free(vf, M_VTFONT);
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}
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}
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static int
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vtfont_validate_map(struct vt_font_map *vfm, unsigned int length,
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unsigned int glyph_count)
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{
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unsigned int i, last = 0;
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for (i = 0; i < length; i++) {
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/* Not ordered. */
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if (i > 0 && vfm[i].vfm_src <= last)
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return (EINVAL);
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/*
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* Destination extends amount of glyphs.
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*/
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if (vfm[i].vfm_dst >= glyph_count ||
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vfm[i].vfm_dst + vfm[i].vfm_len >= glyph_count)
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return (EINVAL);
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last = vfm[i].vfm_src + vfm[i].vfm_len;
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}
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return (0);
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}
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int
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vtfont_load(vfnt_t *f, struct vt_font **ret)
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{
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size_t glyphsize, mapsize;
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struct vt_font *vf;
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int error;
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unsigned int i;
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/* Make sure the dimensions are valid. */
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if (f->width < 1 || f->height < 1)
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return (EINVAL);
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if (f->width > VTFONT_MAXDIMENSION || f->height > VTFONT_MAXDIMENSION ||
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f->glyph_count > VTFONT_MAXGLYPHS)
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return (E2BIG);
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/* Not too many mappings. */
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for (i = 0; i < VFNT_MAPS; i++)
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if (f->map_count[i] > VTFONT_MAXMAPPINGS)
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return (E2BIG);
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/* Character 0 must always be present. */
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if (f->glyph_count < 1)
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return (EINVAL);
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glyphsize = howmany(f->width, 8) * f->height * f->glyph_count;
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if (glyphsize > VTFONT_MAXGLYPHSIZE)
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return (E2BIG);
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/* Allocate new font structure. */
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vf = malloc(sizeof *vf, M_VTFONT, M_WAITOK | M_ZERO);
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vf->vf_bytes = malloc(glyphsize, M_VTFONT, M_WAITOK);
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vf->vf_height = f->height;
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vf->vf_width = f->width;
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vf->vf_refcount = 1;
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/* Allocate, copy in, and validate mappings. */
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for (i = 0; i < VFNT_MAPS; i++) {
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vf->vf_map_count[i] = f->map_count[i];
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if (f->map_count[i] == 0)
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continue;
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mapsize = f->map_count[i] * sizeof(struct vt_font_map);
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vf->vf_map[i] = malloc(mapsize, M_VTFONT, M_WAITOK);
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error = copyin(f->map[i], vf->vf_map[i], mapsize);
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if (error)
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goto bad;
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error = vtfont_validate_map(vf->vf_map[i], vf->vf_map_count[i],
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f->glyph_count);
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if (error)
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goto bad;
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}
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/* Copy in glyph data. */
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error = copyin(f->glyphs, vf->vf_bytes, glyphsize);
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if (error)
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goto bad;
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/* Success. */
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*ret = vf;
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return (0);
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bad: vtfont_unref(vf);
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return (error);
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}
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