<div dir="ltr"><div>Are you able to share a reproducible example?</div><div><br></div><div>The CRAN check report from <a href="https://www.stats.ox.ac.uk/pub/bdr/memtests/clang-ASAN/MatchIt/00check.log">https://www.stats.ox.ac.uk/pub/bdr/memtests/clang-ASAN/MatchIt/00check.log</a> points at <span style="color:rgb(0,0,0);white-space:pre-wrap">MatchIt/src/nnm.cpp:182:24. You could probably distill the code used in that location into a smaller reproducible example.</span></div><div><span style="color:rgb(0,0,0);white-space:pre-wrap"><br></span></div><div><span style="color:rgb(0,0,0);white-space:pre-wrap">Best,</span></div><div><span style="color:rgb(0,0,0);white-space:pre-wrap">Kevin</span></div><div><span style="color:rgb(0,0,0);white-space:pre-wrap"><br></span></div><div><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Sun, Nov 15, 2020 at 3:31 PM Noah Greifer <<a href="mailto:noah.greifer@gmail.com">noah.greifer@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr">Hello,<div><br></div><div>I use Rcpp in the package I maintain, MatchIt. I recently upload it to CRAN with no problems, but then received a message saying there were "additional issues" I needed to address, which were titled clang-ASAN and gcc-ASAN. Looking at the log, it seems that the error was triggered when I used an R function (mahalanobis()) inside the Rcpp code. I realized that I had not properly initialized the function in my Rcpp script. Although the package functions ran correctly, perhaps something about the way the memory was allocated caused this issue. I think I fixed the issue, but I want to check it without uploading it to CRAN again. This issue was not picked up by R cmd check or by the check in winbuilder, so I'm not sure how to check if I have solved the issue. CRAN even accepted my package before letting me know about this issue.</div><div><br></div><div>In searching for solutions to the problem of being able to check whether the issue in my package remains, I came across <a href="http://dirk.eddelbuettel.com/code/sanitizers.html" target="_blank">this</a> article posted by Dirk ("sanitizers: Testing R packages for ASAN and UBSAN errors"). It seems like this article is about using sanitizers, which helps you figure out if your build of R is able to detect the memory allocation errors I was facing, but doesn't give clear instructions on how to set up R to do this. As someone for whom using Rcpp was my first use of programming outside R, the instructions given in the article and in section 4.3 of Writing R Extensions are completely foreign to me and seem to require a deep knowledge of C++. </div><div><br></div><div>I'm wondering if someone can provide me with a clear procedure on how to check if the memory allocation problem still remains in my package. Thank you.</div><div><br></div><div>Noah Greifer</div><div><br></div><div>PS What seems to be the relevant text in the error message is pasted below:</div><div><br></div><div><pre style="color:rgb(0,0,0);white-space:pre-wrap">==1503820==ERROR: AddressSanitizer: stack-use-after-scope on address 0x7ffc220ca7a0 at pc 0x7fc2fb4668ad bp 0x7ffc220ca5b0 sp 0x7ffc220ca5a8
READ of size 8 at 0x7ffc220ca7a0 thread T0
#0 0x7fc2fb4668ac in Rcpp::PreserveStorage<Rcpp::Vector<14, Rcpp::PreserveStorage> >::get__() const /data/gannet/ripley/R/test-clang/Rcpp/include/Rcpp/storage/PreserveStorage.h:26:20
#1 0x7fc2fb4668ac in Rcpp::Vector<14, Rcpp::PreserveStorage>::size() const /data/gannet/ripley/R/test-clang/Rcpp/include/Rcpp/vector/Vector.h:277:39
#2 0x7fc2fb4668ac in Rcpp::sugar::Vectorized<&(sqrt), true, Rcpp::Vector<14, Rcpp::PreserveStorage> >::size() const /data/gannet/ripley/R/test-clang/Rcpp/include/Rcpp/sugar/block/Vectorized_Math.h:40:50</pre><pre style="color:rgb(0,0,0);white-space:pre-wrap">...</pre><pre style="color:rgb(0,0,0);white-space:pre-wrap"><pre style="white-space:pre-wrap">Address 0x7ffc220ca7a0 is located in stack of thread T0 at offset 448 in frame
#0 0x7fc2fb46644f in void Rcpp::Vector<14, Rcpp::PreserveStorage>::assign_sugar_expression<Rcpp::sugar::Vectorized<&(sqrt), true, Rcpp::Vector<14, Rcpp::PreserveStorage> > >(Rcpp::sugar::Vectorized<&(sqrt), true, Rcpp::Vector<14, Rcpp::PreserveStorage> > const&) /data/gannet/ripley/R/test-clang/Rcpp/include/Rcpp/vector/Vector.h:1038
This frame has 1 object(s):
[32, 48) 'ref.tmp.i.i.i.i.i' <== Memory access at offset 448 overflows this variable
HINT: this may be a false positive if your program uses some custom stack unwind mechanism, swapcontext or vfork
(longjmp and C++ exceptions *are* supported)
SUMMARY: AddressSanitizer: stack-use-after-scope /data/gannet/ripley/R/test-clang/Rcpp/include/Rcpp/storage/PreserveStorage.h:26:20 in Rcpp::PreserveStorage<Rcpp::Vector<14, Rcpp::PreserveStorage> >::get__() const
Shadow bytes around the buggy address:
0x1000044114a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00</pre></pre></div></div>
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