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[truetype] Fix `mmvar' array pointers. 

Without this change, clang's AddressSanitizer reports many runtime
errors due to misaligned addresses.

* src/truetype/ttgxvar.c (TT_Get_MM_Var): Use multiples of pointer
size for sub-array offsets into `mmvar'.
This commit is contained in:
Werner Lemberg 2017-09-21 09:03:20 +02:00
parent 843e0dc92b
commit 3b3cb32dd2
2 changed files with 53 additions and 13 deletions
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10
ChangeLog
View File

@ -1,3 +1,13 @@
2017-09-21 Werner Lemberg <wl@gnu.org>
[truetype] Fix `mmvar' array pointers.
Without this change, clang's AddressSanitizer reports many runtime
errors due to misaligned addresses.
* src/truetype/ttgxvar.c (TT_Get_MM_Var): Use multiples of pointer
size for sub-array offsets into `mmvar'.
2017-09-20 Werner Lemberg <wl@gnu.org> 2017-09-20 Werner Lemberg <wl@gnu.org>
[truetype] Integer overflows. [truetype] Integer overflows.

56
src/truetype/ttgxvar.c
View File

@ -1997,6 +1997,14 @@
if ( !face->blend ) if ( !face->blend )
{ {
FT_Offset mmvar_size;
FT_Offset axis_flags_size;
FT_Offset axis_size;
FT_Offset namedstyle_size;
FT_Offset next_coords_size;
FT_Offset next_name_size;
FT_TRACE2(( "FVAR " )); FT_TRACE2(( "FVAR " ));
/* both `fvar' and `gvar' must be present */ /* both `fvar' and `gvar' must be present */
@ -2045,13 +2053,34 @@
/* prepare storage area for MM data; this cannot overflow */ /* prepare storage area for MM data; this cannot overflow */
/* 32-bit arithmetic because of the size limits used in the */ /* 32-bit arithmetic because of the size limits used in the */
/* `fvar' table validity check in `sfnt_init_face' */ /* `fvar' table validity check in `sfnt_init_face' */
face->blend->mmvar_len =
sizeof ( FT_MM_Var ) + /* the various `*_size' variables, which we also use as */
fvar_head.axisCount * sizeof ( FT_UShort ) + /* offsets into the `mmlen' array, must be multiples of the */
fvar_head.axisCount * sizeof ( FT_Var_Axis ) + /* pointer size (except the last one); without such an */
num_instances * sizeof ( FT_Var_Named_Style ) + /* alignment there might be runtime errors due to */
num_instances * fvar_head.axisCount * sizeof ( FT_Fixed ) + /* misaligned addresses */
fvar_head.axisCount * 5; #undef ALIGN_SIZE
#define ALIGN_SIZE( n ) \
( ( (n) + sizeof (void*) - 1 ) & ~( sizeof (void*) - 1 ) )
mmvar_size = ALIGN_SIZE( sizeof ( FT_MM_Var ) );
axis_flags_size = ALIGN_SIZE( fvar_head.axisCount *
sizeof ( FT_UShort ) );
axis_size = ALIGN_SIZE( fvar_head.axisCount *
sizeof ( FT_Var_Axis ) );
namedstyle_size = ALIGN_SIZE( num_instances *
sizeof ( FT_Var_Named_Style ) );
next_coords_size = ALIGN_SIZE( num_instances *
fvar_head.axisCount *
sizeof ( FT_Fixed ) );
next_name_size = fvar_head.axisCount * 5;
face->blend->mmvar_len = mmvar_size +
axis_flags_size +
axis_size +
namedstyle_size +
next_coords_size +
next_name_size;
if ( FT_ALLOC( mmvar, face->blend->mmvar_len ) ) if ( FT_ALLOC( mmvar, face->blend->mmvar_len ) )
goto Exit; goto Exit;
@ -2071,21 +2100,22 @@
/* alas, no public field in `FT_Var_Axis' for axis flags */ /* alas, no public field in `FT_Var_Axis' for axis flags */
axis_flags = axis_flags =
(FT_UShort*)&( mmvar[1] ); (FT_UShort*)( (char*)mmvar + mmvar_size );
mmvar->axis = mmvar->axis =
(FT_Var_Axis*)&( axis_flags[fvar_head.axisCount] ); (FT_Var_Axis*)( (char*)axis_flags + axis_flags_size );
mmvar->namedstyle = mmvar->namedstyle =
(FT_Var_Named_Style*)&( mmvar->axis[fvar_head.axisCount] ); (FT_Var_Named_Style*)( (char*)mmvar->axis + axis_size );
next_coords = next_coords = (FT_Fixed*)( (char*)mmvar->namedstyle +
(FT_Fixed*)&( mmvar->namedstyle[num_instances] ); namedstyle_size );
for ( i = 0; i < num_instances; i++ ) for ( i = 0; i < num_instances; i++ )
{ {
mmvar->namedstyle[i].coords = next_coords; mmvar->namedstyle[i].coords = next_coords;
next_coords += fvar_head.axisCount; next_coords += fvar_head.axisCount;
} }
next_name = (FT_String*)next_coords; next_name = (FT_String*)( (char*)mmvar->namedstyle +
namedstyle_size + next_coords_size );
for ( i = 0; i < fvar_head.axisCount; i++ ) for ( i = 0; i < fvar_head.axisCount; i++ )
{ {
mmvar->axis[i].name = next_name; mmvar->axis[i].name = next_name;