[LLVMdev] Fix crash in llvm_gcda_emit_arcs()

Joseph Kain joekain at gmail.com
Thu Sep 5 09:46:54 PDT 2013

Hi Nick,

Thanks for looking over my patch.  I'd be happy to add the compare against
cur_buffer_size.  I'll try to write up such a change today and then send a
new patch to the list.

Joseph Kain

On Thu, Sep 5, 2013 at 1:37 AM, Nick Lewycky <nicholas at mxc.ca> wrote:

> Bill, could you take a look at this? I don't have a checkout of
> compiler-rt that builds.
> It seems obviously-correct to me, but I wish it did a compare against
> cur_buffer_size to make sure it's in range.
> Nick
> Joseph Kain wrote:
>> Hi,
>> I've been seeing a crash in llvm_gcda_emit_arcs() on x86_64.  The crash
>> occurs executing a movdqa instruction with an unaligned src address.
>>   The attached patch to the compiler-rt project fixes the problem by
>> using memcpy() to read data from the write_buffer[] in GCDAProfiling.c.
>> This is my first patch submission to llvm so please let me know if I've
>> missed any steps.  I'm not on the mailing list so please include me on
>> any replies.
>> I haven't run the tests on this change but would be happy to do so if
>> someone could point me to documentation on how to do so.  I couldn't
>> find testing instructions linked from
>> http://llvm.org/docs/**DeveloperPolicy.html<http://llvm.org/docs/DeveloperPolicy.html>.
>>  I have built the change and
>> run it with the programs I was testing originally.  With this change the
>> crash no longer occurs.
>> Thanks,
>> Joseph Kain
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Joseph Kain
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