Oracle Java Runtime Environment - Heap Out-of-Bounds Read During TTF Font Rendering in OpenTypeLayoutEngine::adjustGlyphPositions

2019-02-18 19:05:16

A heap-based out-of-bounds read was observed in Oracle Java Runtime Environment version 8u202 (latest at the time of this writing) while fuzz-testing the processing of TrueType fonts. It manifests itself in the form of the following (or similar) crash:

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$ bin/java -cp . DisplaySfntFont test.ttf
Iteration (0,0)
Iteration (0,1)
Iteration (0,2)
Iteration (0,3)
Iteration (0,4)
#
# A fatal error has been detected by the Java Runtime Environment:
#
# SIGSEGV (0xb) at pc=0x00007fbaa11694c8, pid=19540, tid=0x00007fbac4f18700
#
# JRE version: Java(TM) SE Runtime Environment (8.0_202-b08) (build 1.8.0_202-b08)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (25.202-b08 mixed mode linux-amd64 compressed oops)
# Problematic frame:
# C [libfontmanager.so+0x284c8] OpenTypeLayoutEngine::adjustGlyphPositions(unsigned short const*, int, int, char, LEGlyphStorage&, LEErrorCode&)+0x268
#
# Failed to write core dump. Core dumps have been disabled. To enable core dumping, try "ulimit -c unlimited" before starting Java again
#
# An error report file with more information is saved as:
# jre/8u202/hs_err_pid19540.log
#
# If you would like to submit a bug report, please visit:
# http://bugreport.java.com/bugreport/crash.jsp
# The crash happened outside the Java Virtual Machine in native code.
# See problematic frame for where to report the bug.
#
Aborted
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Under gdb, we can find out that the OpenTypeLayoutEngine::adjustGlyphPositions function attempts to access an invalid memory region:

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gdb-peda$ c
Continuing.
Iteration (0,0)
Iteration (0,1)
Iteration (0,2)
Iteration (0,3)
Iteration (0,4)

Thread 2 "java" received signal SIGSEGV, Segmentation fault.
[----------------------------------registers-----------------------------------]
RAX: 0x7ffff0283cc0 --> 0x0
[...]
[-------------------------------------code-------------------------------------]
0x7fffc41cb4bb <_ZN20OpenTypeLayoutEngine20adjustGlyphPositionsEPKtiicR14LEGlyphStorageR11LEErrorCode+603>: nop DWORD PTR [rax+rax*1+0x0]
0x7fffc41cb4c0 <_ZN20OpenTypeLayoutEngine20adjustGlyphPositionsEPKtiicR14LEGlyphStorageR11LEErrorCode+608>: lea rax,[rax+rax*4]
0x7fffc41cb4c4 <_ZN20OpenTypeLayoutEngine20adjustGlyphPositionsEPKtiicR14LEGlyphStorageR11LEErrorCode+612>: lea rax,[rdx+rax*4]
=> 0x7fffc41cb4c8 <_ZN20OpenTypeLayoutEngine20adjustGlyphPositionsEPKtiicR14LEGlyphStorageR11LEErrorCode+616>: addss xmm0,DWORD PTR [rax]
0x7fffc41cb4cc <_ZN20OpenTypeLayoutEngine20adjustGlyphPositionsEPKtiicR14LEGlyphStorageR11LEErrorCode+620>: addss xmm1,DWORD PTR [rax+0x4]
0x7fffc41cb4d1 <_ZN20OpenTypeLayoutEngine20adjustGlyphPositionsEPKtiicR14LEGlyphStorageR11LEErrorCode+625>: movsxd rax,DWORD PTR [rax+0x10]
0x7fffc41cb4d5 <_ZN20OpenTypeLayoutEngine20adjustGlyphPositionsEPKtiicR14LEGlyphStorageR11LEErrorCode+629>: test eax,eax
0x7fffc41cb4d7 <_ZN20OpenTypeLayoutEngine20adjustGlyphPositionsEPKtiicR14LEGlyphStorageR11LEErrorCode+631>:
jns 0x7fffc41cb4c0 <_ZN20OpenTypeLayoutEngine20adjustGlyphPositionsEPKtiicR14LEGlyphStorageR11LEErrorCode+608>
[------------------------------------stack-------------------------------------]
[...]
[------------------------------------------------------------------------------]
Legend: code, data, rodata, value
Stopped reason: SIGSEGV
0x00007fffc41cb4c8 in OpenTypeLayoutEngine::adjustGlyphPositions(unsigned short const*, int, int, char, LEGlyphStorage&, LEErrorCode&) ()
from jre/8u202/lib/amd64/libfontmanager.so
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The crash reproduces on both Windows and Linux platforms. On Windows, the crash manifests in the following way:

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(3798.db8): Access violation - code c0000005 (first chance)
First chance exceptions are reported before any exception handling.
This exception may be expected and handled.
fontmanager!Java_sun_java2d_loops_DrawGlyphListLCD_DrawGlyphListLCD+0x13346:
00007ffa`0c9eb046 8b448a10 mov eax,dword ptr [rdx+rcx*4+10h] ds:00000000`69815274=????????
0:004> ? rdx
Evaluate expression: 1696397556 = 00000000`651cf8f4
0:004> ? rcx
Evaluate expression: 18421340 = 00000000`0119165c
0:004> k
# Child-SP RetAddr Call Site
00 00000000`055ce250 00007ffa`0c9e3c3f fontmanager!Java_sun_java2d_loops_DrawGlyphListLCD_DrawGlyphListLCD+0x13346
01 00000000`055ce3c0 00007ffa`0c9ef6fe fontmanager!Java_sun_java2d_loops_DrawGlyphListLCD_DrawGlyphListLCD+0xbf3f
02 00000000`055ce420 00000000`056e8d27 fontmanager!Java_sun_font_SunLayoutEngine_nativeLayout+0x21e
03 00000000`055ce750 00000000`055ce750 0x56e8d27
04 00000000`055ce758 00000000`5cb9a4a8 0x55ce750
05 00000000`055ce760 00000000`055ce7c0 0x5cb9a4a8
06 00000000`055ce768 00000000`5cb3fd68 0x55ce7c0
07 00000000`055ce770 00000000`055ce8e8 0x5cb3fd68
08 00000000`055ce778 00000000`00000000 0x55ce8e8
--- cut ---

Attached with this report are three mutated testcases, and a simple Java program used to reproduce the vulnerability by loading TrueType fonts specified through a command-line parameter.


Proof of Concept:
https://github.com/offensive-security/exploitdb-bin-sploits/raw/master/bin-sploits/46410.zip

Fixes

No fixes

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