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[cid] Add a bunch of safety checks. 

* src/cid/cidload.c (parse_fd_array): Check `num_dicts' against
stream size.
(cid_read_subrs): Check largest offset against stream size.
(cid_parse_dict): Move safety check to ...
(cid_face_open): ... this function.
Also test length of binary data and values of `SDBytes',
`SubrMapOffset', `SubrCount', `CIDMapOffset', and `CIDCount'.
This commit is contained in:
Werner Lemberg 2015-10-20 22:31:57 +02:00
parent d47d372c96
commit 3eccc3a3f8
2 changed files with 132 additions and 23 deletions
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12
ChangeLog
View File

@ -1,3 +1,15 @@
2015-10-20 Werner Lemberg <wl@gnu.org>
[cid] Add a bunch of safety checks.
* src/cid/cidload.c (parse_fd_array): Check `num_dicts' against
stream size.
(cid_read_subrs): Check largest offset against stream size.
(cid_parse_dict): Move safety check to ...
(cid_face_open): ... this function.
Also test length of binary data and values of `SDBytes',
`SubrMapOffset', `SubrCount', `CIDMapOffset', and `CIDCount'.
2015-10-20 Werner Lemberg <wl@gnu.org>
[cid] Avoid segfault with malformed input (#46250).

139
src/cid/cidload.c
View File

@ -215,6 +215,7 @@
{
CID_FaceInfo cid = &face->cid;
FT_Memory memory = face->root.memory;
FT_Stream stream = parser->stream;
FT_Error error = FT_Err_Ok;
FT_Long num_dicts;
@ -227,6 +228,31 @@
goto Exit;
}
/*
* A single entry in the FDArray must (at least) contain the following
* structure elements.
*
* %ADOBeginFontDict 18
* X dict begin 13
* /FontMatrix [X X X X] 22
* /Private X dict begin 22
* end 4
* end 4
* %ADOEndFontDict 16
*
* This needs 18+13+22+22+4+4+16=99 bytes or more. Normally, you also
* need a `dup X' at the very beginning and a `put' at the end, so a
* rough guess using 100 bytes as the minimum is justified.
*/
if ( (FT_ULong)num_dicts > stream->size / 100 )
{
FT_TRACE0(( "parse_fd_array: adjusting FDArray size"
" (from %d to %d)\n",
num_dicts,
stream->size / 100 ));
num_dicts = (FT_Long)( stream->size / 100 );
}
if ( !cid->font_dicts )
{
FT_Int n;
@ -401,16 +427,6 @@
FT_ERROR(( "cid_parse_dict: No font dictionary found\n" ));
return FT_THROW( Invalid_File_Format );
}
/* allow at most 32bit offsets */
if ( face->cid.fd_bytes > 4 || face->cid.gd_bytes > 4 )
{
FT_ERROR(( "cid_parse_dict:"
" Values of `FDBytes' or `GDBytes' larger than 4\n"
" "
" are not supported\n" ));
return FT_THROW( Invalid_File_Format );
}
}
return parser->root.error;
@ -445,13 +461,6 @@
FT_Byte* p;
/* Check for possible overflow. */
if ( num_subrs == FT_UINT_MAX )
{
error = FT_THROW( Syntax_Error );
goto Fail;
}
/* reallocate offsets array if needed */
if ( num_subrs + 1 > max_offsets )
{
@ -485,8 +494,15 @@
for ( count = 1; count <= num_subrs; count++ )
if ( offsets[count - 1] > offsets[count] )
{
FT_TRACE1(( "cid_read_subrs: offsets are not ordered\n" ));
error = FT_THROW( Syntax_Error );
FT_ERROR(( "cid_read_subrs: offsets are not ordered\n" ));
error = FT_THROW( Invalid_File_Format );
goto Fail;
}
if ( offsets[num_subrs] > stream->size - cid->data_offset )
{
FT_ERROR(( "cid_read_subrs: too large `subrs' offsets\n" ));
error = FT_THROW( Invalid_File_Format );
goto Fail;
}
@ -675,6 +691,12 @@
CID_Parser* parser;
FT_Memory memory = face->root.memory;
FT_Error error;
FT_Int n;
CID_FaceInfo cid = &face->cid;
FT_ULong binary_length;
FT_ULong entry_len;
cid_init_loader( &loader, face );
@ -699,6 +721,17 @@
if ( parser->binary_length )
{
if ( parser->binary_length >
face->root.stream->size - parser->data_offset )
{
FT_TRACE0(( "cid_face_open: adjusting length of binary data\n"
" (from %d to %d bytes)\n",
parser->binary_length,
face->root.stream->size - parser->data_offset ));
parser->binary_length = face->root.stream->size -
parser->data_offset;
}
/* we must convert the data section from hexadecimal to binary */
if ( FT_ALLOC( face->binary_data, parser->binary_length ) ||
cid_hex_to_binary( face->binary_data, parser->binary_length,
@ -707,14 +740,78 @@
FT_Stream_OpenMemory( face->cid_stream,
face->binary_data, parser->binary_length );
face->cid.data_offset = 0;
cid->data_offset = 0;
}
else
{
*face->cid_stream = *face->root.stream;
face->cid.data_offset = loader.parser.data_offset;
cid->data_offset = loader.parser.data_offset;
}
/* sanity tests */
/* allow at most 32bit offsets */
if ( cid->fd_bytes > 4 || cid->gd_bytes > 4 )
{
FT_ERROR(( "cid_parse_dict:"
" Values of `FDBytes' or `GDBytes' larger than 4\n"
" "
" are not supported\n" ));
error = FT_THROW( Invalid_File_Format );
goto Exit;
}
binary_length = face->cid_stream->size - cid->data_offset;
entry_len = (FT_ULong)( cid->fd_bytes + cid->gd_bytes );
for ( n = 0; n < cid->num_dicts; n++ )
{
CID_FaceDict dict = cid->font_dicts + n;
if ( dict->sd_bytes > 4 )
{
FT_ERROR(( "cid_parse_dict:"
" Values of `SDBytes' larger than 4"
" are not supported\n" ));
error = FT_THROW( Invalid_File_Format );
goto Exit;
}
if ( dict->subrmap_offset > binary_length )
{
FT_ERROR(( "cid_parse_dict: Invalid `SubrMapOffset' value\n" ));
error = FT_THROW( Invalid_File_Format );
goto Exit;
}
if ( dict->sd_bytes &&
dict->num_subrs >
( binary_length - dict->subrmap_offset ) / dict->sd_bytes )
{
FT_ERROR(( "cid_parse_dict: Invalid `SubrCount' value\n" ));
error = FT_THROW( Invalid_File_Format );
goto Exit;
}
}
if ( cid->cidmap_offset > binary_length )
{
FT_ERROR(( "cid_parse_dict: Invalid `CIDMapOffset' value\n" ));
error = FT_THROW( Invalid_File_Format );
goto Exit;
}
if ( entry_len &&
cid->cid_count >
( binary_length - cid->cidmap_offset ) / entry_len )
{
FT_ERROR(( "cid_parse_dict: Invalid `CIDCount' value\n" ));
error = FT_THROW( Invalid_File_Format );
goto Exit;
}
/* we can now safely proceed */
error = cid_read_subrs( face );
Exit: