Commit fba29fabb3c3892ccd8afc3a9c3988aaeb036dc8
2015-10-27T21:04:48
[pfr] Add some safety guards (#46302). * src/pfr/pfrload.h (PFR_CHECK): Rename to... (PFR_CHECK_SIZE): ... this. (PFR_SIZE): [!PFR_CONFIG_NO_CHECKS]: Define to PFR_CHECK_SIZE. * src/pfr/pfrload.c (pfr_log_font_count): Check `count'. (pfr_extra_item_load_kerning_pairs): Remove tracing message. (pfr_phy_font_load): Use PFR_CHECK_SIZE where appropriate. Allocate `chars' after doing a size checks. * src/pfr/pfrsbit.c (pfr_load_bitmap_bits): Move test for invalid bitmap format to... (pfr_slot_load_bitmap): ... this function. Check bitmap size.
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diff --git a/ChangeLog b/ChangeLog
index a19acf0..8c618cc 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,21 @@
+2015-10-27 Werner Lemberg <wl@gnu.org>
+
+ [pfr] Add some safety guards (#46302).
+
+ * src/pfr/pfrload.h (PFR_CHECK): Rename to...
+ (PFR_CHECK_SIZE): ... this.
+ (PFR_SIZE): [!PFR_CONFIG_NO_CHECKS]: Define to PFR_CHECK_SIZE.
+
+ * src/pfr/pfrload.c (pfr_log_font_count): Check `count'.
+ (pfr_extra_item_load_kerning_pairs): Remove tracing message.
+ (pfr_phy_font_load): Use PFR_CHECK_SIZE where appropriate.
+ Allocate `chars' after doing a size checks.
+
+ * src/pfr/pfrsbit.c (pfr_load_bitmap_bits): Move test for invalid
+ bitmap format to...
+ (pfr_slot_load_bitmap): ... this function.
+ Check bitmap size.
+
2015-10-26 Werner Lemberg <wl@gnu.org>
[truetype] Fix sanitizing logic for `loca' (#46223).
diff --git a/src/pfr/pfrload.c b/src/pfr/pfrload.c
index a1cae2c..ed8327a 100644
--- a/src/pfr/pfrload.c
+++ b/src/pfr/pfrload.c
@@ -26,6 +26,93 @@
#define FT_COMPONENT trace_pfr
+ /*
+ * The overall structure of a PFR file is as follows.
+ *
+ * PFR header
+ * 58 bytes (contains nPhysFonts)
+ *
+ * Logical font directory (size at most 2^16 bytes)
+ * 2 bytes (nLogFonts)
+ * + nLogFonts * 5 bytes
+ *
+ * ==> nLogFonts <= 13106
+ *
+ * Logical font section (size at most 2^24 bytes)
+ * nLogFonts * logFontRecord
+ *
+ * logFontRecord (size at most 2^16 bytes)
+ * 12 bytes (fontMatrix)
+ * + 1 byte (flags)
+ * + 0-5 bytes (depending on `flags')
+ * + 0-(1+255*(2+255)) = 0-65536 (depending on `flags')
+ * + 5 bytes (physical font info)
+ * + 0-1 bytes (depending on PFR header)
+ *
+ * ==> minimum size 18 bytes
+ *
+ * Physical font section (size at most 2^24 bytes)
+ * nPhysFonts * (physFontRecord
+ * + nBitmapSizes * nBmapChars * bmapCharRecord)
+ *
+ * physFontRecord (size at most 2^24 bytes)
+ * 14 bytes (font info)
+ * + 1 byte (flags)
+ * + 0-2 (depending on `flags')
+ * + 0-? (structure too complicated to be shown here; depending on
+ * `flags'; contains `nBitmapSizes' and `nBmapChars')
+ * + 3 bytes (nAuxBytes)
+ * + nAuxBytes
+ * + 1 byte (nBlueValues)
+ * + 2 * nBlueValues
+ * + 6 bytes (hinting data)
+ * + 2 bytes (nCharacters)
+ * + nCharacters * (4-10 bytes) (depending on `flags')
+ *
+ * ==> minimum size 27 bytes
+ *
+ * bmapCharRecord
+ * 4-7 bytes
+ *
+ * Glyph program strings (three possible types: simpleGps, compoundGps,
+ * and bitmapGps; size at most 2^24 bytes)
+ * simpleGps (size at most 2^16 bytes)
+ * 1 byte (flags)
+ * 1-2 bytes (n[XY]orus, depending on `flags')
+ * 0-(64+512*2) = 0-1088 bytes (depending on `n[XY]orus')
+ * 0-? (structure too complicated to be shown here; depending on
+ * `flags')
+ * 1-? glyph data (faintly resembling PS Type 1 charstrings)
+ *
+ * ==> minimum size 3 bytes
+ *
+ * compoundGps (size at most 2^16 bytes)
+ * 1 byte (nElements <= 63, flags)
+ * + 0-(1+255*(2+255)) = 0-65536 (depending on `flags')
+ * + nElements * (6-14 bytes)
+ *
+ * bitmapGps (size at most 2^16 bytes)
+ * 1 byte (flags)
+ * 3-13 bytes (position info, depending on `flags')
+ * 0-? bitmap data
+ *
+ * ==> minimum size 4 bytes
+ *
+ * PFR trailer
+ * 8 bytes
+ *
+ *
+ * ==> minimum size of a valid PFR:
+ * 58 (header)
+ * + 2 (nLogFonts)
+ * + 27 (1 physFontRecord)
+ * + 8 (trailer)
+ * -----
+ * 95 bytes
+ *
+ */
+
+
/*************************************************************************/
/*************************************************************************/
/***** *****/
@@ -212,6 +299,16 @@
FT_READ_USHORT( count ) )
goto Exit;
+ /* check maximum value and a rough minimum size */
+ if ( count > ( ( 1 << 16 ) - 2 ) / 5 ||
+ 2 + count * 5 >= stream->size - section_offset )
+ {
+ FT_ERROR(( "pfr_log_font_count:"
+ " invalid number of logical fonts\n" ));
+ error = FT_THROW( Invalid_Table );
+ goto Exit;
+ }
+
result = count;
Exit:
@@ -530,8 +627,6 @@
FT_Memory memory = phy_font->memory;
- FT_TRACE2(( "pfr_extra_item_load_kerning_pairs()\n" ));
-
if ( FT_NEW( item ) )
goto Exit;
@@ -782,7 +877,7 @@
FT_Byte* q2;
- PFR_CHECK( num_aux );
+ PFR_CHECK_SIZE( num_aux );
p += num_aux;
while ( num_aux > 0 )
@@ -871,9 +966,6 @@
phy_font->num_chars = count = PFR_NEXT_USHORT( p );
phy_font->chars_offset = offset + (FT_Offset)( p - stream->cursor );
- if ( FT_NEW_ARRAY( phy_font->chars, count ) )
- goto Fail;
-
Size = 1 + 1 + 2;
if ( flags & PFR_PHY_2BYTE_CHARCODE )
Size += 1;
@@ -890,7 +982,10 @@
if ( flags & PFR_PHY_3BYTE_GPS_OFFSET )
Size += 1;
- PFR_CHECK( count * Size );
+ PFR_CHECK_SIZE( count * Size );
+
+ if ( FT_NEW_ARRAY( phy_font->chars, count ) )
+ goto Fail;
for ( n = 0; n < count; n++ )
{
diff --git a/src/pfr/pfrload.h b/src/pfr/pfrload.h
index 0a51234..867e632 100644
--- a/src/pfr/pfrload.h
+++ b/src/pfr/pfrload.h
@@ -25,14 +25,19 @@
FT_BEGIN_HEADER
+ /* some size checks should be always done (mainly to prevent */
+ /* excessive allocation for malformed data), ... */
+#define PFR_CHECK_SIZE( x ) do \
+ { \
+ if ( p + (x) > limit ) \
+ goto Too_Short; \
+ } while ( 0 )
+
+ /* ... and some only if intensive checking is explicitly requested */
#ifdef PFR_CONFIG_NO_CHECKS
#define PFR_CHECK( x ) do { } while ( 0 )
#else
-#define PFR_CHECK( x ) do \
- { \
- if ( p + (x) > limit ) \
- goto Too_Short; \
- } while ( 0 )
+#define PFR_CHECK PFR_CHECK_SIZE
#endif
#define PFR_NEXT_BYTE( p ) FT_NEXT_BYTE( p )
diff --git a/src/pfr/pfrsbit.c b/src/pfr/pfrsbit.c
index bed082e..a219636 100644
--- a/src/pfr/pfrsbit.c
+++ b/src/pfr/pfrsbit.c
@@ -510,8 +510,7 @@
break;
default:
- FT_ERROR(( "pfr_read_bitmap_data: invalid image type\n" ));
- error = FT_THROW( Invalid_File_Format );
+ ;
}
}
@@ -633,6 +632,53 @@
&advance, &format );
/*
+ * Before allocating the target bitmap, we check whether the given
+ * bitmap dimensions are valid, depending on the image format.
+ *
+ * Format 0: We have a stream of pixels (with 8 pixels per byte).
+ *
+ * (xsize * ysize + 7) / 8 <= gps_size
+ *
+ * Format 1: Run-length encoding; the high nibble holds the number of
+ * white bits, the low nibble the number of black bits. In
+ * other words, a single byte can represent at most 15
+ * pixels.
+ *
+ * xsize * ysize <= 15 * gps_size
+ *
+ * Format 2: Run-length encoding; the high byte holds the number of
+ * white bits, the low byte the number of black bits. In
+ * other words, two bytes can represent at most 255 pixels.
+ *
+ * xsize * ysize <= 255 * (gps_size + 1) / 2
+ */
+ switch ( format )
+ {
+ case 0:
+ if ( ( (FT_ULong)xsize * ysize + 7 ) / 8 > gps_size )
+ error = FT_THROW( Invalid_Table );
+ break;
+ case 1:
+ if ( (FT_ULong)xsize * ysize > 15 * gps_size )
+ error = FT_THROW( Invalid_Table );
+ break;
+ case 2:
+ if ( (FT_ULong)xsize * ysize > 255 * ( ( gps_size + 1 ) / 2 ) )
+ error = FT_THROW( Invalid_Table );
+ break;
+ default:
+ FT_ERROR(( "pfr_slot_load_bitmap: invalid image type\n" ));
+ error = FT_THROW( Invalid_Table );
+ }
+
+ if ( error )
+ {
+ if ( FT_ERR_EQ( error, Invalid_Table ) )
+ FT_ERROR(( "pfr_slot_load_bitmap: invalid bitmap dimensions\n" ));
+ goto Exit;
+ }
+
+ /*
* XXX: on 16bit systems we return an error for huge bitmaps
* that cause size truncation, because truncated
* size properties make bitmap glyphs broken.