forked from minhngoc25a/freetype2
[cff] Fix boundary checks.
642bc7590c introduced dynamically
allocated memory when parsing CFF files with the "old" engine. Bounds
checks have never been updated, however, leading to pointless
comparisons of pointers in some cases. This commit presents a
solution for bounds checks in the CFF module with an extended logic
for the "old" engine while staying as concise as possible for the
"new" one.
* src/cff/cffparse.h: Introduce the struct `CFF_T2_StringRec' and
the additional field `t2_strings' within `CFF_ParserRec'.
* src/cff/cffparse.c (cff_parser_within_limits): Move all boundary
checks into this new function and update the rest of `cffparse.c' to
use it.
Reported as
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=12137This commit is contained in:
Armin Hasitzka
parent
fdb10e8b50
commit
6986ddac1e
23
ChangeLog
23
ChangeLog
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@ -1,3 +1,26 @@
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2019-03-31 Armin Hasitzka <prince.cherusker@gmail.com>
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[cff] Fix boundary checks.
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642bc7590c701c8cd35a9f60fa899cfa518b17ff introduced dynamically
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allocated memory when parsing CFF files with the "old" engine. Bounds
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checks have never been updated, however, leading to pointless
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comparisons of pointers in some cases. This commit presents a
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solution for bounds checks in the CFF module with an extended logic
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for the "old" engine while staying as concise as possible for the
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"new" one.
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* src/cff/cffparse.h: Introduce the struct `CFF_T2_StringRec' and
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the additional field `t2_strings' within `CFF_ParserRec'.
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* src/cff/cffparse.c (cff_parser_within_limits): Move all boundary
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checks into this new function and update the rest of `cffparse.c' to
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use it.
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Reported as
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https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=12137
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2019-03-20 Werner Lemberg <wl@gnu.org>
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[autofit] Fix Mongolian blue zone characters.
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@ -77,6 +77,23 @@
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}
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#ifdef CFF_CONFIG_OPTION_OLD_ENGINE
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static void
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finalize_t2_strings( FT_Memory memory,
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void* data,
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void* user )
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{
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CFF_T2_String t2 = (CFF_T2_String)data;
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FT_UNUSED( user );
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memory->free( memory, t2->start );
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memory->free( memory, data );
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}
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#endif /* CFF_CONFIG_OPTION_OLD_ENGINE */
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FT_LOCAL_DEF( void )
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cff_parser_done( CFF_Parser parser )
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{
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@ -84,13 +101,65 @@
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FT_FREE( parser->stack );
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#ifdef CFF_CONFIG_OPTION_OLD_ENGINE
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FT_List_Finalize( &parser->t2_strings,
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finalize_t2_strings,
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memory,
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NULL );
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#endif
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}
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/* Assuming `first >= last'. */
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static FT_Error
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cff_parser_within_limits( CFF_Parser parser,
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FT_Byte* first,
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FT_Byte* last )
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{
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#ifndef CFF_CONFIG_OPTION_OLD_ENGINE
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/* Fast path for regular FreeType builds with the "new" engine; */
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/* `first >= parser->start' can be assumed. */
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FT_UNUSED( first );
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return last < parser->limit ? FT_Err_Ok : FT_THROW( Invalid_Argument );
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#else /* CFF_CONFIG_OPTION_OLD_ENGINE */
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FT_ListNode node;
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if ( first >= parser->start &&
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last < parser->limit )
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return FT_Err_Ok;
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node = parser->t2_strings.head;
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while ( node )
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{
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CFF_T2_String t2 = (CFF_T2_String)node->data;
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if ( first >= t2->start &&
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last < t2->limit )
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return FT_Err_Ok;
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node = node->next;
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}
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return FT_THROW( Invalid_Argument );
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#endif /* CFF_CONFIG_OPTION_OLD_ENGINE */
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}
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/* read an integer */
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static FT_Long
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cff_parse_integer( FT_Byte* start,
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FT_Byte* limit )
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cff_parse_integer( CFF_Parser parser,
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FT_Byte* start )
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{
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FT_Byte* p = start;
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FT_Int v = *p++;
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@ -99,14 +168,14 @@
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if ( v == 28 )
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{
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if ( p + 2 > limit )
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if ( cff_parser_within_limits( parser, p, p + 1 ) )
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goto Bad;
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val = (FT_Short)( ( (FT_UShort)p[0] << 8 ) | p[1] );
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}
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else if ( v == 29 )
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{
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if ( p + 4 > limit )
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if ( cff_parser_within_limits( parser, p, p + 3 ) )
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goto Bad;
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val = (FT_Long)( ( (FT_ULong)p[0] << 24 ) |
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@ -120,14 +189,14 @@
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}
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else if ( v < 251 )
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{
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if ( p + 1 > limit )
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if ( cff_parser_within_limits( parser, p, p ) )
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goto Bad;
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val = ( v - 247 ) * 256 + p[0] + 108;
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}
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else
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{
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if ( p + 1 > limit )
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if ( cff_parser_within_limits( parser, p, p ) )
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goto Bad;
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val = -( v - 251 ) * 256 - p[0] - 108;
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@ -176,10 +245,10 @@
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/* read a real */
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static FT_Fixed
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cff_parse_real( FT_Byte* start,
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FT_Byte* limit,
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FT_Long power_ten,
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FT_Long* scaling )
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cff_parse_real( CFF_Parser parser,
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FT_Byte* start,
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FT_Long power_ten,
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FT_Long* scaling )
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{
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FT_Byte* p = start;
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FT_Int nib;
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@ -214,7 +283,7 @@
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p++;
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/* Make sure we don't read past the end. */
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if ( p >= limit )
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if ( cff_parser_within_limits( parser, p, p ) )
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goto Bad;
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}
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@ -251,7 +320,7 @@
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p++;
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/* Make sure we don't read past the end. */
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if ( p >= limit )
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if ( cff_parser_within_limits( parser, p, p ) )
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goto Bad;
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}
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@ -290,7 +359,7 @@
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p++;
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/* Make sure we don't read past the end. */
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if ( p >= limit )
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if ( cff_parser_within_limits( parser, p, p ) )
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goto Bad;
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}
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@ -457,7 +526,7 @@
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if ( **d == 30 )
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{
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/* binary-coded decimal is truncated to integer */
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return cff_parse_real( *d, parser->limit, 0, NULL ) >> 16;
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return cff_parse_real( parser, *d, 0, NULL ) >> 16;
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}
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else if ( **d == 255 )
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@ -483,7 +552,7 @@
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}
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else
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return cff_parse_integer( *d, parser->limit );
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return cff_parse_integer( parser, *d );
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}
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@ -494,10 +563,10 @@
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FT_Long scaling )
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{
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if ( **d == 30 )
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return cff_parse_real( *d, parser->limit, scaling, NULL );
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return cff_parse_real( parser, *d, scaling, NULL );
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else
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{
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FT_Long val = cff_parse_integer( *d, parser->limit );
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FT_Long val = cff_parse_integer( parser, *d );
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if ( scaling )
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@ -562,14 +631,14 @@
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FT_ASSERT( scaling );
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if ( **d == 30 )
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return cff_parse_real( *d, parser->limit, 0, scaling );
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return cff_parse_real( parser, *d, 0, scaling );
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else
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{
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FT_Long number;
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FT_Int integer_length;
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number = cff_parse_integer( d[0], d[1] );
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number = cff_parse_integer( parser, d[0] );
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if ( number > 0x7FFFL )
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{
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@ -1122,18 +1191,6 @@
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#endif /* FT_DEBUG_LEVEL_TRACE */
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#ifdef CFF_CONFIG_OPTION_OLD_ENGINE
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static void
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destruct_t2s_item( FT_Memory memory,
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void* data,
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void* user )
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{
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FT_UNUSED( user );
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memory->free( memory, data );
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}
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#endif /* CFF_CONFIG_OPTION_OLD_ENGINE */
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FT_LOCAL_DEF( FT_Error )
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cff_parser_run( CFF_Parser parser,
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FT_Byte* start,
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@ -1147,11 +1204,6 @@
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FT_Library library = parser->library;
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FT_Memory memory = library->memory;
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FT_ListRec t2s;
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FT_ZERO( &t2s );
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#endif
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parser->top = parser->stack;
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@ -1212,9 +1264,11 @@
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FT_Byte* charstring_base;
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FT_ULong charstring_len;
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FT_Fixed* stack;
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FT_ListNode node;
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FT_Byte* q;
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FT_Fixed* stack;
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FT_ListNode node;
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CFF_T2_String t2;
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size_t t2_size;
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FT_Byte* q;
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charstring_base = ++p;
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@ -1261,16 +1315,26 @@
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if ( !node )
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goto Out_Of_Memory_Error;
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FT_List_Add( &parser->t2_strings, node );
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t2 = (CFF_T2_String)memory->alloc( memory,
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sizeof ( CFF_T2_StringRec ) );
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if ( !t2 )
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goto Out_Of_Memory_Error;
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node->data = t2;
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/* `5' is the conservative upper bound of required bytes per stack */
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/* element. */
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q = (FT_Byte*)memory->alloc( memory,
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5 * ( decoder.top - decoder.stack ) );
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t2_size = 5 * ( decoder.top - decoder.stack );
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q = (FT_Byte*)memory->alloc( memory, t2_size );
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if ( !q )
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goto Out_Of_Memory_Error;
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node->data = q;
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FT_List_Add( &t2s, node );
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t2->start = q;
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t2->limit = q + t2_size;
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stack = decoder.stack;
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@ -1531,9 +1595,6 @@
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} /* while ( p < limit ) */
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Exit:
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#ifdef CFF_CONFIG_OPTION_OLD_ENGINE
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FT_List_Finalize( &t2s, destruct_t2s_item, memory, NULL );
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#endif
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return error;
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#ifdef CFF_CONFIG_OPTION_OLD_ENGINE
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@ -60,6 +60,10 @@ FT_BEGIN_HEADER
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FT_Byte** top;
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FT_UInt stackSize; /* allocated size */
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#ifdef CFF_CONFIG_OPTION_OLD_ENGINE
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FT_ListRec t2_strings;
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#endif /* CFF_CONFIG_OPTION_OLD_ENGINE */
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FT_UInt object_code;
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void* object;
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@ -130,6 +134,15 @@ FT_BEGIN_HEADER
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FT_END_HEADER
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#ifdef CFF_CONFIG_OPTION_OLD_ENGINE
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typedef struct CFF_T2_String_
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{
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FT_Byte* start;
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FT_Byte* limit;
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} CFF_T2_StringRec, *CFF_T2_String;
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#endif /* CFF_CONFIG_OPTION_OLD_ENGINE */
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#endif /* CFFPARSE_H_ */
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