[lld] r341670 - MachO: Fix out-of-bounds memory access in getString16

Tom Stellard via llvm-commits llvm-commits at lists.llvm.org
Fri Sep 7 09:03:55 PDT 2018


On 09/07/2018 08:48 AM, Tom Stellard via llvm-commits wrote:
> On 09/07/2018 08:42 AM, Tom Stellard via llvm-commits wrote:
>> Author: tstellar
>> Date: Fri Sep  7 08:42:01 2018
>> New Revision: 341670
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=341670&view=rev
>> Log:
>> MachO: Fix out-of-bounds memory access in getString16
>>
>> Summary:
>> This fixes the following tests when gcc is compiled with gcc8:
>>
>> lld :: mach-o/do-not-emit-unwind-fde-arm64.yaml
>> lld :: mach-o/eh-frame-relocs-arm64.yaml
>>
>> llvm.org/PR38096
>>
> 
> Hans,
> 
> This is a fix for the release blocker: llvm.org/PR38096.  Is ths
> OK to merge to the release_70 branch?
> 

We will need to pull in the follow-up r341672 too.

-Tom

> -Tom
> 
>> Reviewers: lhames, kledzik, javed.absar
>>
>> Subscribers: kristof.beyls, llvm-commits
>>
>> Differential Revision: https://reviews.llvm.org/D51547
>>
>> Modified:
>>     lld/trunk/lib/ReaderWriter/MachO/MachONormalizedFileBinaryUtils.h
>>
>> Modified: lld/trunk/lib/ReaderWriter/MachO/MachONormalizedFileBinaryUtils.h
>> URL: http://llvm.org/viewvc/llvm-project/lld/trunk/lib/ReaderWriter/MachO/MachONormalizedFileBinaryUtils.h?rev=341670&r1=341669&r2=341670&view=diff
>> ==============================================================================
>> --- lld/trunk/lib/ReaderWriter/MachO/MachONormalizedFileBinaryUtils.h (original)
>> +++ lld/trunk/lib/ReaderWriter/MachO/MachONormalizedFileBinaryUtils.h Fri Sep  7 08:42:01 2018
>> @@ -185,12 +185,11 @@ packRelocation(const Relocation &r, bool
>>    return result;
>>  }
>>  
>> -inline StringRef getString16(const char s[16]) {
>> -  StringRef x = s;
>> -  if ( x.size() > 16 )
>> -    return x.substr(0, 16);
>> -  else
>> -    return x;
>> +static StringRef getString16(const char s[16]) {
>> +  // The StringRef(const char *) constructor passes the const char * to
>> +  // strlen(), so we can't use this constructor here, because if there is no
>> +  // null terminator in s, then strlen() will read past the end of the array.
>> +  return StringRef(s, strnlen(s, 16));
>>  }
>>  
>>  inline void setString16(StringRef str, char s[16]) {
>>
>>
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> 
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