pdfium stack-based buffer overflow in CPDF_Function::Call

The following crash was encountered in pdfium (the Chrome PDF renderer) during 
PDF fuzzing:

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$ ./pdfium_test asan_stack-oob_b9a750_1372_52559cc9c86b4bc0fb43218c7f69c5c8 
Rendering PDF file asan_stack-oob_b9a750_1372_52559cc9c86b4bc0fb43218c7f69c5c8.
Non-linearized path...
=================================================================
==22207==ERROR: AddressSanitizer: stack-buffer-overflow on address 
0x7ffc8b7edb84 at pc 0x000000d6f064 bp 0x7ffc8b7ed8c0 sp 0x7ffc8b7ed8b8
READ of size 4 at 0x7ffc8b7edb84 thread T0
    #0 0xd6f063 in CPDF_Function::Call(float*, int, float*, int&) const core/src/fpdfapi/fpdf_page/fpdf_page_func.cpp:896:9
    #1 0xd6ecd2 in CPDF_StitchFunc::v_Call(float*, float*) const core/src/fpdfapi/fpdf_page/fpdf_page_func.cpp:808:3
    #2 0xd6f6a7 in CPDF_Function::Call(float*, int, float*, int&) const core/src/fpdfapi/fpdf_page/fpdf_page_func.cpp:902:3
    #3 0xedbc22 in DrawFuncShading(CFX_DIBitmap*, CFX_Matrix*, CPDF_Dictionary*, CPDF_Function**, int, CPDF_ColorSpace*, int) core/src/fpdfapi/fpdf_render/fpdf_render_pattern.cpp:293:15
    #4 0xeda3c0 in CPDF_RenderStatus::DrawShading(CPDF_ShadingPattern*, CFX_Matrix*, FX_RECT&, int, int) core/src/fpdfapi/fpdf_render/fpdf_render_pattern.cpp:875:7
    #5 0xee45b9 in CPDF_RenderStatus::ProcessShading(CPDF_ShadingObject*, CFX_Matrix const*) core/src/fpdfapi/fpdf_render/fpdf_render_pattern.cpp:954:3
    #6 0xe6700d in CPDF_RenderStatus::ProcessObjectNoClip(CPDF_PageObject const*, CFX_Matrix const*) core/src/fpdfapi/fpdf_render/fpdf_render.cpp:399:14
    #7 0xe61f6d in CPDF_RenderStatus::RenderSingleObject(CPDF_PageObject const*, CFX_Matrix const*) core/src/fpdfapi/fpdf_render/fpdf_render.cpp:292:3
    #8 0xe618c1 in CPDF_RenderStatus::RenderObjectList(CPDF_PageObjects const*, CFX_Matrix const*) core/src/fpdfapi/fpdf_render/fpdf_render.cpp:269:5
    #9 0xe6bc26 in CPDF_RenderStatus::ProcessForm(CPDF_FormObject*, CFX_Matrix const*) core/src/fpdfapi/fpdf_render/fpdf_render.cpp:485:3
    #10 0xe6704c in CPDF_RenderStatus::ProcessObjectNoClip(CPDF_PageObject const*, CFX_Matrix const*) core/src/fpdfapi/fpdf_render/fpdf_render.cpp:402:14
    #11 0xe67f47 in CPDF_RenderStatus::ContinueSingleObject(CPDF_PageObject const*, CFX_Matrix const*, IFX_Pause*) core/src/fpdfapi/fpdf_render/fpdf_render.cpp:330:3
    #12 0xe76f12 in CPDF_ProgressiveRenderer::Continue(IFX_Pause*) core/src/fpdfapi/fpdf_render/fpdf_render.cpp:1152:13
    #13 0xe756c1 in CPDF_ProgressiveRenderer::Start(IFX_Pause*) core/src/fpdfapi/fpdf_render/fpdf_render.cpp:1090:3
    #14 0x63dbd7 in FPDF_RenderPage_Retail(CRenderContext*, void*, int, int, int, int, int, int, int, IFSDK_PAUSE_Adapter*) fpdfsdk/src/fpdfview.cpp:752:3
    #15 0x63c3af in FPDF_RenderPageBitmap fpdfsdk/src/fpdfview.cpp:507:3
    #16 0x4ee0df in RenderPage(std::string const&, void* const&, void* const&, int, Options const&) samples/pdfium_test.cc:374:3
    #17 0x4f0af8 in RenderPdf(std::string const&, char const*, unsigned long, Options const&) samples/pdfium_test.cc:531:9
    #18 0x4f16e9 in main samples/pdfium_test.cc:608:5

Address 0x7ffc8b7edb84 is located in stack of thread T0 at offset 36 in frame
    #0 0xd6e2af in CPDF_StitchFunc::v_Call(float*, float*) const core/src/fpdfapi/fpdf_page/fpdf_page_func.cpp:795

  This frame has 2 object(s):
    [32, 36) 'input' <== Memory access at offset 36 overflows this variable
    [48, 52) 'nresults'
HINT: this may be a false positive if your program uses some custom stack 
unwind mechanism or swapcontext
      (longjmp and C++ exceptions *are* supported)
SUMMARY: AddressSanitizer: stack-buffer-overflow 
core/src/fpdfapi/fpdf_page/fpdf_page_func.cpp:896:9 in 
CPDF_Function::Call(float*, int, float*, int&) const
Shadow bytes around the buggy address:
  0x1000116f5b20: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x1000116f5b30: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x1000116f5b40: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x1000116f5b50: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x1000116f5b60: 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1
=>0x1000116f5b70:[04]f2 04 f3 00 00 00 00 00 00 00 00 00 00 00 00
  0x1000116f5b80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x1000116f5b90: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x1000116f5ba0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x1000116f5bb0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x1000116f5bc0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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
==22207==ABORTING
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While the sample crashes on a memory read operation in AddressSanitizer, an 
out-of-bounds "write" takes place subsequently in the same method, leading to a 
stack-based buffer overflow condition.

The crash was reported at 
https://code.google.com/p/chromium/issues/detail?id=551460. Attached is the PDF 
file which triggers the crash.

This bug is subject to a 90 day disclosure deadline. If 90 days elapse without 
a broadly available patch, then the bug report will automatically become 
visible to the public.
Original issue reported on code.google.com by mjurc...@google.com on 4 Nov 2015 at 4:43
Attachments:
asan_stack-oob_b9a750_1372_52559cc9c86b4bc0fb43218c7f69c5c8.pdf
Anon777 / google-security-research

pdfium stack-based buffer overflow in CPDF_Function::Call #612
