From 4a808ed163df1057031bc6d085300fe1ef6f57d2 Mon Sep 17 00:00:00 2001 From: Michael Schroeder Date: Fri, 8 Jun 2012 20:29:54 -0700 Subject: [PATCH] [perl #111610] Trouble with XS-APItest/t/clone-with-stack.t I ran into a bit of a problem when building perl-5.16.0. 'make test' showed a segfault in ext/XS-APItest/t/clone-with-stack.t. It seems to be caused by accessing already freed memory, it segfaults because I have MALLOC_PERTUBE_ set, thus glibc fills freed memory with some value. Digging deeper, it seems like perl_clone() does not fix the cx's blk_oldcop element when doing context cloning, thus blk_oldcop still points to PL_compiling in the old interp--the calling scope for the BEGIN block being the compilation of the code surrounding it--and the POPBLOCK done in leavesub will copy the data from the old interp to PL_curcop. After fixing this, it still crashed because interp_dup->Iop was zero after the runops_standard() call (which is probably correct as the end of the BEGIN block was reached). So I also added an if statement that checks the pointer. --- ext/XS-APItest/APItest.xs | 3 ++- sv.c | 1 + 2 files changed, 3 insertions(+), 1 deletion(-) diff --git a/ext/XS-APItest/APItest.xs b/ext/XS-APItest/APItest.xs index 2c0ee61..69b7066 100644 --- a/ext/XS-APItest/APItest.xs +++ b/ext/XS-APItest/APItest.xs @@ -3084,7 +3084,8 @@ CODE: PERL_SET_CONTEXT(interp_dup); /* continue after 'clone_with_stack' */ - interp_dup->Iop = interp_dup->Iop->op_next; + if (interp_dup->Iop) + interp_dup->Iop = interp_dup->Iop->op_next; /* run with new perl */ Perl_runops_standard(interp_dup); diff --git a/sv.c b/sv.c index 2034c00..fcd76a9 100644 --- a/sv.c +++ b/sv.c @@ -12312,6 +12312,7 @@ Perl_cx_dup(pTHX_ PERL_CONTEXT *cxs, I32 ix, I32 max, CLONE_PARAMS* param) Perl_croak(aTHX_ "Cloning substitution context is unimplemented"); } else { + ncx->blk_oldcop = (COP*)any_dup(ncx->blk_oldcop, param->proto_perl); switch (CxTYPE(ncx)) { case CXt_SUB: ncx->blk_sub.cv = (ncx->blk_sub.olddepth == 0 -- 1.7.11.4