ref: e838c37c2c1575eb12116ce6303ffacc72521ce8
parent: 3876846e26fdd56f4434bdabfe6722ec66a40b83
author: Ben Wagner <bungeman@chromium.org>
date: Tue Jan 11 06:14:32 EST 2022
[type42] Track how much type42 ttf data is available. Currently `T42_Open_Face` eagerly allocates 12 bytes for the ttf header data which it expects `t42_parse_sfnts` to fill out from /sfnts data. However, there is no guarantee that `t42_parse_sfnts` will actually be called while parsing the type42 data as the /sfnts array may be missing or very short. This is also confusing behavior as it means `T42_Open_Face` is tightly coupled to the implementation of the very distant `t42_parse_sfnts` code which requires at least 12 bytes to already be reserved in `face->ttf_data`. `t42_parse_sfnts` itself eagerly updates `face->ttf_size` to track how much space is reserved for ttf data instead of traking how much data has actually been written into `face->ttf_data`. It will also act strangely in the presense of multiple /sfnts arrays. * src/type42/t42objs.c (T42_Open_Face): ensure `ttf_data` is initialized to NULL. Free `ttf_data` on error. * src/type42/t42parse.c (t42_parse_sfnts): delay setting `ttf_size` and set it to the actual number of bytes read. Ensure `ttf_data` is freed if there are multiple /sfnts arrays or there are any errors.
--- a/src/type42/t42objs.c
+++ b/src/type42/t42objs.c
@@ -44,16 +44,9 @@
parser = &loader.parser;
- /* To handle buggy fonts we don't use `FT_QALLOC` here. */
- if ( FT_ALLOC( face->ttf_data, 12 ) )
- goto Exit;
+ face->ttf_data = NULL;
+ face->ttf_size = 0;
- /* while parsing the font we always update `face->ttf_size' so that */
- /* even in case of buggy data (which might lead to premature end of */
- /* scanning without causing an error) the call to `FT_Open_Face' in */
- /* `T42_Face_Init' passes the correct size */
- face->ttf_size = 12;
-
error = t42_parser_init( parser,
face->root.stream,
memory,
@@ -153,6 +146,11 @@
Exit:
t42_loader_done( &loader );
+ if ( error )
+ {+ FT_FREE(face->ttf_data);
+ face->ttf_size = 0;
+ }
return error;
}
--- a/src/type42/t42parse.c
+++ b/src/type42/t42parse.c
@@ -538,7 +538,8 @@
FT_Byte* limit = parser->root.limit;
FT_Error error;
FT_Int num_tables = 0;
- FT_Long count;
+ FT_Long ttf_count;
+ FT_Long ttf_reserved;
FT_ULong n, string_size, old_string_size, real_size;
FT_Byte* string_buf = NULL;
@@ -546,6 +547,9 @@
T42_Load_Status status;
+ /** There should only be one sfnts array, but free any previous. */
+ FT_FREE( face->ttf_data );
+ face->ttf_size = 0;
/* The format is */
/* */
@@ -574,7 +578,10 @@
status = BEFORE_START;
string_size = 0;
old_string_size = 0;
- count = 0;
+ ttf_count = 0;
+ ttf_reserved = 12;
+ if ( FT_QALLOC( face->ttf_data, ttf_reserved ) )
+ goto Fail;
FT_TRACE2(( "\n" ));
FT_TRACE2(( "t42_parse_sfnts:\n" ));
@@ -589,6 +596,7 @@
if ( *cur == ']' )
{parser->root.cursor++;
+ face->ttf_size = ttf_count;
goto Exit;
}
@@ -684,7 +692,7 @@
}
FT_TRACE2(( " PS string size %5lu bytes, offset 0x%08lx (%lu)\n",
- string_size, count, count ));
+ string_size, ttf_count, ttf_count ));
/* The whole TTF is now loaded into `string_buf'. We are */
/* checking its contents while copying it to `ttf_data'. */
@@ -697,21 +705,24 @@
{case BEFORE_START:
/* load offset table, 12 bytes */
- if ( count < 12 )
+ if ( ttf_count < 12 )
{- face->ttf_data[count++] = string_buf[n];
+ face->ttf_data[ttf_count++] = string_buf[n];
continue;
}
else
{- num_tables = 16 * face->ttf_data[4] + face->ttf_data[5];
- status = BEFORE_TABLE_DIR;
- face->ttf_size = 12 + 16 * num_tables;
+ FT_Long ttf_reserved_prev = ttf_reserved;
+
+ num_tables = 16 * face->ttf_data[4] + face->ttf_data[5];
+ status = BEFORE_TABLE_DIR;
+ ttf_reserved = 12 + 16 * num_tables;
+
FT_TRACE2(( " SFNT directory contains %d tables\n",
num_tables ));
- if ( (FT_Long)size < face->ttf_size )
+ if ( (FT_Long)size < ttf_reserved )
{FT_ERROR(( "t42_parse_sfnts: invalid data in sfnts array\n" ));
error = FT_THROW( Invalid_File_Format );
@@ -718,9 +729,8 @@
goto Fail;
}
- /* To handle bad fonts with an invalid table directory */
- /* we don't use `FT_QREALLOC` here. */
- if ( FT_REALLOC( face->ttf_data, 12, face->ttf_size ) )
+ if ( FT_QREALLOC( face->ttf_data, ttf_reserved_prev,
+ ttf_reserved ) )
goto Fail;
}
/* fall through */
@@ -727,9 +737,9 @@
case BEFORE_TABLE_DIR:
/* the offset table is read; read the table directory */
- if ( count < face->ttf_size )
+ if ( ttf_count < ttf_reserved )
{- face->ttf_data[count++] = string_buf[n];
+ face->ttf_data[ttf_count++] = string_buf[n];
continue;
}
else
@@ -736,6 +746,7 @@
{int i;
FT_ULong len;
+ FT_Long ttf_reserved_prev = ttf_reserved;
FT_TRACE2(( "\n" ));
@@ -751,7 +762,7 @@
FT_TRACE2(( " %4i 0x%08lx (%lu)\n", i, len, len ));
if ( len > size ||
- face->ttf_size > (FT_Long)( size - len ) )
+ ttf_reserved > (FT_Long)( size - len ) )
{FT_ERROR(( "t42_parse_sfnts:"
" invalid data in sfnts array\n" ));
@@ -760,22 +771,18 @@
}
/* Pad to a 4-byte boundary length */
- face->ttf_size += (FT_Long)( ( len + 3 ) & ~3U );
+ ttf_reserved += (FT_Long)( ( len + 3 ) & ~3U );
}
+ ttf_reserved += 1;
status = OTHER_TABLES;
FT_TRACE2(( "\n" ));
- FT_TRACE2(( " allocating %ld bytes\n", face->ttf_size + 1 ));
+ FT_TRACE2(( " allocating %ld bytes\n", ttf_reserved ));
FT_TRACE2(( "\n" ));
- /* To handle bad fonts we don't use `FT_QREALLOC` here: */
- /* chances are high that due to incorrect values in the */
- /* table directory the computation of `ttf_size` would be */
- /* incorrect otherwise, causing run-time errors because of */
- /* accessing uninitialized memory. */
- if ( FT_REALLOC( face->ttf_data, 12 + 16 * num_tables,
- face->ttf_size + 1 ) )
+ if ( FT_QREALLOC( face->ttf_data, ttf_reserved_prev,
+ ttf_reserved ) )
goto Fail;
}
/* fall through */
@@ -782,13 +789,13 @@
case OTHER_TABLES:
/* all other tables are just copied */
- if ( count >= face->ttf_size )
+ if ( ttf_count >= ttf_reserved )
{FT_ERROR(( "t42_parse_sfnts: too much binary data\n" ));
error = FT_THROW( Invalid_File_Format );
goto Fail;
}
- face->ttf_data[count++] = string_buf[n];
+ face->ttf_data[ttf_count++] = string_buf[n];
}
}
@@ -802,6 +809,11 @@
parser->root.error = error;
Exit:
+ if ( parser->root.error )
+ {+ FT_FREE( face->ttf_data );
+ face->ttf_size = 0;
+ }
if ( allocated )
FT_FREE( string_buf );
}