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[cff, truetype] Integer overflows. 

Reported as

  https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=2075
  https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=2088

* src/cff/cf2font.c (cf2_font_setup): Use OVERFLOW_MUL_INT32.

* src/truetype/ttinterp.c (Ins_ISECT): Use OVERFLOW_MUL_LONG,
OVERFLOW_ADD_LONG, and OVERFLOW_SUB_LONG.
This commit is contained in:
Werner Lemberg 2017-06-04 20:43:08 +02:00
parent addb2dddb6
commit 9fa8a2997f
3 changed files with 41 additions and 23 deletions
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14
ChangeLog
View File

@ -1,3 +1,17 @@
2017-06-04 Werner Lemberg <wl@gnu.org>
[cff, truetype] Integer overflows.
Reported as
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=2075
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=2088
* src/cff/cf2font.c (cf2_font_setup): Use OVERFLOW_MUL_INT32.
* src/truetype/ttinterp.c (Ins_ISECT): Use OVERFLOW_MUL_LONG,
OVERFLOW_ADD_LONG, and OVERFLOW_SUB_LONG.
2017-06-03 Werner Lemberg <wl@gnu.org>
[base, cff, truetype] Integer overflows.

2
src/cff/cf2font.c
View File

@ -447,7 +447,7 @@
/* choose a constant for StdHW that depends on font contrast */
stdHW = cf2_getStdHW( decoder );
if ( stdHW > 0 && font->stdVW > 2 * stdHW )
if ( stdHW > 0 && font->stdVW > OVERFLOW_MUL_INT32( 2, stdHW ) )
font->stdHW = FT_DivFix( cf2_intToFixed( 75 ), emRatio );
else
{

48
src/truetype/ttinterp.c
View File

@ -6455,19 +6455,19 @@
/* Cramer's rule */
dbx = exc->zp0.cur[b1].x - exc->zp0.cur[b0].x;
dby = exc->zp0.cur[b1].y - exc->zp0.cur[b0].y;
dbx = OVERFLOW_SUB_LONG( exc->zp0.cur[b1].x, exc->zp0.cur[b0].x );
dby = OVERFLOW_SUB_LONG( exc->zp0.cur[b1].y, exc->zp0.cur[b0].y );
dax = exc->zp1.cur[a1].x - exc->zp1.cur[a0].x;
day = exc->zp1.cur[a1].y - exc->zp1.cur[a0].y;
dax = OVERFLOW_SUB_LONG( exc->zp1.cur[a1].x, exc->zp1.cur[a0].x );
day = OVERFLOW_SUB_LONG( exc->zp1.cur[a1].y, exc->zp1.cur[a0].y );
dx = exc->zp0.cur[b0].x - exc->zp1.cur[a0].x;
dy = exc->zp0.cur[b0].y - exc->zp1.cur[a0].y;
dx = OVERFLOW_SUB_LONG( exc->zp0.cur[b0].x, exc->zp1.cur[a0].x );
dy = OVERFLOW_SUB_LONG( exc->zp0.cur[b0].y, exc->zp1.cur[a0].y );
discriminant = FT_MulDiv( dax, -dby, 0x40 ) +
FT_MulDiv( day, dbx, 0x40 );
dotproduct = FT_MulDiv( dax, dbx, 0x40 ) +
FT_MulDiv( day, dby, 0x40 );
discriminant = OVERFLOW_ADD_LONG( FT_MulDiv( dax, -dby, 0x40 ),
FT_MulDiv( day, dbx, 0x40 ) );
dotproduct = OVERFLOW_ADD_LONG( FT_MulDiv( dax, dbx, 0x40 ),
FT_MulDiv( day, dby, 0x40 ) );
/* The discriminant above is actually a cross product of vectors */
/* da and db. Together with the dot product, they can be used as */
@ -6477,30 +6477,34 @@
/* discriminant = |da||db|sin(angle) . */
/* We use these equations to reject grazing intersections by */
/* thresholding abs(tan(angle)) at 1/19, corresponding to 3 degrees. */
if ( 19 * FT_ABS( discriminant ) > FT_ABS( dotproduct ) )
if ( OVERFLOW_MUL_LONG( 19, FT_ABS( discriminant ) ) >
FT_ABS( dotproduct ) )
{
val = FT_MulDiv( dx, -dby, 0x40 ) + FT_MulDiv( dy, dbx, 0x40 );
val = OVERFLOW_ADD_LONG( FT_MulDiv( dx, -dby, 0x40 ),
FT_MulDiv( dy, dbx, 0x40 ) );
R.x = FT_MulDiv( val, dax, discriminant );
R.y = FT_MulDiv( val, day, discriminant );
/* XXX: Block in backward_compatibility and/or post-IUP? */
exc->zp2.cur[point].x = exc->zp1.cur[a0].x + R.x;
exc->zp2.cur[point].y = exc->zp1.cur[a0].y + R.y;
exc->zp2.cur[point].x = OVERFLOW_ADD_LONG( exc->zp1.cur[a0].x, R.x );
exc->zp2.cur[point].y = OVERFLOW_ADD_LONG( exc->zp1.cur[a0].y, R.y );
}
else
{
/* else, take the middle of the middles of A and B */
/* XXX: Block in backward_compatibility and/or post-IUP? */
exc->zp2.cur[point].x = ( exc->zp1.cur[a0].x +
exc->zp1.cur[a1].x +
exc->zp0.cur[b0].x +
exc->zp0.cur[b1].x ) / 4;
exc->zp2.cur[point].y = ( exc->zp1.cur[a0].y +
exc->zp1.cur[a1].y +
exc->zp0.cur[b0].y +
exc->zp0.cur[b1].y ) / 4;
exc->zp2.cur[point].x =
OVERFLOW_ADD_LONG( OVERFLOW_ADD_LONG( exc->zp1.cur[a0].x,
exc->zp1.cur[a1].x ),
OVERFLOW_ADD_LONG( exc->zp0.cur[b0].x,
exc->zp0.cur[b1].x ) ) / 4;
exc->zp2.cur[point].y =
OVERFLOW_ADD_LONG( OVERFLOW_ADD_LONG( exc->zp1.cur[a0].y,
exc->zp1.cur[a1].y ),
OVERFLOW_ADD_LONG( exc->zp0.cur[b0].y,
exc->zp0.cur[b1].y ) ) / 4;
}
exc->zp2.tags[point] |= FT_CURVE_TAG_TOUCH_BOTH;