[Rcpp-devel] Possible regression in R-3.2.3 or Rcpp 0.12.3

[Qiang Kou]

Hi, Kevin, I was also trying to track this down yesterday.

>From the debugging info below, *indices_n* is not equal to length of
*indices*, which I don't quite understand.

Program received signal SIGSEGV, Segmentation fault.

0x00007ffff2ed5c4e in Rcpp::SubsetProxy<13, Rcpp::PreserveStorage, 13,
true, Rcpp::sugar::Minus_Vector_Primitive<13, true, Rcpp::Vector<13,
Rcpp::PreserveStorage> > >::get_vec (this=this at entry=0x7fffffff79a0)

    at
/usr/local/lib/R/site-library/Rcpp/include/Rcpp/vector/Subsetter.h:200

199             output[i] = lhs[ indices[i] ];

(gdb) p i

$1 = 33622

(gdb) p indices[i]

Cannot access memory at address 0x34c6e000

(gdb) p indices_n

$2 = 9594546

On Fri, Jan 29, 2016 at 2:29 PM, Dirk Eddelbuettel <edd at debian.org> wrote:

>
> On 29 January 2016 at 11:27, Kevin Ushey wrote:
> | When I add some debug printing to the associated subscripting line
> | (
> https://github.com/awalker89/openxlsx/blob/b92bb3acdd6ea759be928c298c6faeef2f26fa3e/src/cppFunctions.cpp#L2608
> ),
> | I see:
> |
> |    colNumbers.size(): 98,03,150
> |    charCols.size(): 95,94,546
> |
> | It looks to me like the package is erroneously attempting to subset
> | vectors of different sizes, causing out-of-bounds reads.
>
> Nice work.
>
> | Unfortunately, Rcpp is not detecting or warning about this...
> |
> | Either way, I believe this is a bug in the openxlsx package, but Rcpp
> | should be checking / reporting this.
>
> With (Rcpp)Armadillo you do have an option of turning this on/off. With
> Rcpp
> alone not quite.
>
> Dirk
>
> --
> http://dirk.eddelbuettel.com | @eddelbuettel | edd at debian.org
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-- 
Qiang Kou
qkou at umail.iu.edu
School of Informatics and Computing, Indiana University
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