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Sanitizer fixes #9239

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Merged
merged 2 commits into from
Sep 28, 2017
Merged

Sanitizer fixes #9239

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3520374
Fix leak of FreeType glyphs.
QuLogic Sep 26, 2017
0067441
Always NUL-terminate TrueType font table buffer.
QuLogic Sep 27, 2017
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5 changes: 4 additions & 1 deletion extern/ttconv/pprdrv_tt.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -137,7 +137,7 @@ BYTE *GetTable(struct TTFONT *font, const char *name)

offset = getULONG( ptr + 8 );
length = getULONG( ptr + 12 );
table = (BYTE*)calloc( sizeof(BYTE), length );
table = (BYTE*)calloc( sizeof(BYTE), length + 2 );
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This looks a bit tricky to review, can you provide a pointer (hehe) to where you expect table to be null-terminated?

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Well, there's only one more diff chunk in this file. ;)

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I know, but what I mean is that it's not clear from the codeflow how the return value of GetTable is later used with the expectation that it is null-terminated. (I am not asking you to unwrap the whole codeflow, just some hint that this is correct...)

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Ah, you mean where the code expects NUL-termination? See the backtrace in the commit:

ERROR: AddressSanitizer: heap-buffer-overflow on address 0x617000235709 at pc 0x7f95efd3c48a bp 0x7ffe41b6ecc0 sp 0x7ffe41b6ecb0
READ of size 1 at 0x617000235709 thread T0
    #0 0x7f95efd3c489 in utf16be_to_ascii extern/ttconv/pprdrv_tt.cpp:178
    #1 0x7f95efd3c489 in Read_name(TTFONT*) extern/ttconv/pprdrv_tt.cpp:339
    #2 0x7f95efd499ef in read_font(...) extern/ttconv/pprdrv_tt.cpp:1325
    #3 0x7f95efd4c602 in get_pdf_charprocs(...) extern/ttconv/pprdrv_tt.cpp:1420
    #4 0x7f95efd35c22 in py_get_pdf_charprocs src/_ttconv.cpp:217

0x617000235709 is located 1 bytes to the right of 648-byte region [0x617000235480,0x617000235708)
allocated by thread T0 here:
    #0 0x7f9612262a38 in __interceptor_calloc (/usr/lib64/libasan.so.4+0xdea38)
    #1 0x7f95efd3b261 in GetTable(TTFONT*, char const*) extern/ttconv/pprdrv_tt.cpp:140

Read_name calls utf16be_to_ascii with some pointer in the middle of the table + a length, but it also checks for NUL-termination to ensure no overflows.

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Ah, I see, should have read the commit message :-) Thanks!


try
{
Expand All @@ -160,6 +160,9 @@ BYTE *GetTable(struct TTFONT *font, const char *name)
free(table);
throw;
}
/* Always NUL-terminate; add two in case of UTF16 strings. */
table[length] = '\0';
table[length + 1] = '\0';
return table;
}

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4 changes: 1 addition & 3 deletions src/ft2font.cpp
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Expand Up @@ -601,9 +601,7 @@ void FT2Font::set_text(
FT_Bool use_kerning = FT_HAS_KERNING(face);
FT_UInt previous = 0;

glyphs.resize(0);
pen.x = 0;
pen.y = 0;
clear();
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@anntzer anntzer Sep 27, 2017 •
edited
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Note for the future reviewer: this additionally calls FT_Done_Glyph on each element of glyph.
This parts looks good to me.


bbox.xMin = bbox.yMin = 32000;
bbox.xMax = bbox.yMax = -32000;
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