发布 2016-05-26 漏洞条目

Graphite2 – GlyphCache::Loader Heap Overreads

Exploit Source

Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=751

The following crashes due to two different heap-based buffer overreads can be observed in an ASAN build of the standard Graphite2 gr2FontTest utility (git trunk), triggered with the following command:

$ ./gr2fonttest /path/to/file -auto

While we have seen the crashes to occur with six unique call stacks, eventually the OOB reads happen at two code locations: graphite2::GlyphCache::Loader::Loader (graphite/src/GlyphCache.cpp:306:38) and graphite2::GlyphCache::Loader::read_glyph (graphite/src/GlyphCache.cpp:398:27). Below you can see the ASAN reports of crashes in both functions:

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==26347==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x60c00000bf40 at pc 0x00000055445d bp 0x7ffe231e8130 sp 0x7ffe231e8128

READ of size 1 at 0x60c00000bf40 thread T0

#0 0x55445c in unsigned long be::_peek<1>(unsigned char const*) graphite/src/./inc/Endian.h:77:73

#1 0x5543c8 in unsigned long be::_peek<2>(unsigned char const*) graphite/src/./inc/Endian.h:50:43

#2 0x551eab in unsigned short be::read<unsigned short>(unsigned char const*&) graphite/src/./inc/Endian.h:60:23

#3 0x562a66 in graphite2::GlyphCache::Loader::read_glyph(unsigned short, graphite2::GlyphFace&, int*) const graphite/src/GlyphCache.cpp:398:27

#4 0x560481 in graphite2::GlyphCache::GlyphCache(graphite2::Face const&, unsigned int) graphite/src/GlyphCache.cpp:142:37

#5 0x54bb13 in graphite2::Face::readGlyphs(unsigned int) graphite/src/Face.cpp:98:29

#6 0x56fb34 in (anonymous namespace)::load_face(graphite2::Face&, unsigned int) graphite/src/gr_face.cpp:54:14

#7 0x56f644 in gr_make_face_with_ops graphite/src/gr_face.cpp:89:16

#8 0x571980 in gr_make_file_face graphite/src/gr_face.cpp:242:23

#9 0x4ecf13 in Parameters::testFileFont() const (graphite/gr2fonttest/gr2fonttest+0x4ecf13)

#10 0x4f0387 in main (graphite/gr2fonttest/gr2fonttest+0x4f0387)

0x60c00000bf40 is located 0 bytes to the right of 128-byte region [0x60c00000bec0,0x60c00000bf40)

allocated by thread T0 here:

#0 0x4b85b8 in malloc llvm/projects/compiler-rt/lib/asan/asan_malloc_linux.cc:40

#1 0x55dc0b in graphite2::FileFace::get_table_fn(void const*, unsigned int, unsigned long*) graphite/src/FileFace.cpp:94:11

#2 0x54f8b1 in graphite2::Face::Table::Table(graphite2::Face const&, graphite2::TtfUtil::Tag, unsigned int) graphite/src/Face.cpp:280:36

#3 0x567867 in graphite2::GlyphCache::Loader::Loader(graphite2::Face const&, bool) graphite/src/GlyphCache.cpp:268:24

#4 0x55ef50 in graphite2::GlyphCache::GlyphCache(graphite2::Face const&, unsigned int) graphite/src/GlyphCache.cpp:118:21

#5 0x54bb13 in graphite2::Face::readGlyphs(unsigned int) graphite/src/Face.cpp:98:29

#6 0x56fb34 in (anonymous namespace)::load_face(graphite2::Face&, unsigned int) graphite/src/gr_face.cpp:54:14

#7 0x56f644 in gr_make_face_with_ops graphite/src/gr_face.cpp:89:16

#8 0x571980 in gr_make_file_face graphite/src/gr_face.cpp:242:23

#9 0x4ecf13 in Parameters::testFileFont() const (graphite/gr2fonttest/gr2fonttest+0x4ecf13)

#10 0x4f0387 in main (graphite/gr2fonttest/gr2fonttest+0x4f0387)

SUMMARY: AddressSanitizer: heap-buffer-overflow graphite/src/./inc/Endian.h:77:73 in unsigned long be::_peek<1>(unsigned char const*)

Shadow bytes around the buggy address:

0x0c187fff9790: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa

0x0c187fff97a0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa

0x0c187fff97b0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa

0x0c187fff97c0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa

0x0c187fff97d0: fa fa fa fa fa fa fa fa 00 00 00 00 00 00 00 00

=>0x0c187fff97e0: 00 00 00 00 00 00 00 00[fa]fa fa fa fa fa fa fa

0x0c187fff97f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 07

0x0c187fff9800: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa

0x0c187fff9810: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa

0x0c187fff9820: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa

0x0c187fff9830: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa

Shadow byte legend (one shadow byte represents 8 application bytes):

Addressable: 00

Partially addressable: 01 02 03 04 05 06 07

Heap left redzone: fa

Heap right redzone: fb

Freed heap region: fd

Stack left redzone: f1

Stack mid redzone: f2

Stack right redzone: f3

Stack partial redzone: f4

Stack after return: f5

Stack use after scope: f8

Global redzone: f9

Global init order: f6

Poisoned by user: f7

Container overflow: fc

Array cookie: ac

Intra object redzone: bb

ASan internal: fe

Left alloca redzone: ca

Right alloca redzone: cb

==26347==ABORTING

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==26561==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x60200000efb7 at pc 0x00000055445d bp 0x7ffc518d4260 sp 0x7ffc518d4258

READ of size 1 at 0x60200000efb7 thread T0

#0 0x55445c in unsigned long be::_peek<1>(unsigned char const*) graphite/src/./inc/Endian.h:77:73

#1 0x5543c8 in unsigned long be::_peek<2>(unsigned char const*) graphite/src/./inc/Endian.h:50:43

#2 0x554358 in unsigned long be::_peek<4>(unsigned char const*) graphite/src/./inc/Endian.h:50:43

#3 0x551d6b in unsigned int be::read<unsigned int>(unsigned char const*&) graphite/src/./inc/Endian.h:60:23

#4 0x5685a5 in graphite2::GlyphCache::Loader::Loader(graphite2::Face const&, bool) graphite/src/GlyphCache.cpp:306:38

#5 0x55ef50 in graphite2::GlyphCache::GlyphCache(graphite2::Face const&, unsigned int) graphite/src/GlyphCache.cpp:118:21

#6 0x54bb13 in graphite2::Face::readGlyphs(unsigned int) graphite/src/Face.cpp:98:29

#7 0x56fb34 in (anonymous namespace)::load_face(graphite2::Face&, unsigned int) graphite/src/gr_face.cpp:54:14

#8 0x56f644 in gr_make_face_with_ops graphite/src/gr_face.cpp:89:16

#9 0x571980 in gr_make_file_face graphite/src/gr_face.cpp:242:23

#10 0x4ecf13 in Parameters::testFileFont() const (graphite/gr2fonttest/gr2fonttest+0x4ecf13)

#11 0x4f0387 in main (graphite/gr2fonttest/gr2fonttest+0x4f0387)

0x60200000efb7 is located 0 bytes to the right of 7-byte region [0x60200000efb0,0x60200000efb7)