add assertion to prevent stack corruption in XSUB

We should not be able to return negative offsets from the stack in XSUBs.
Perl · Oct 2, 2015 · 9e77582 · 9e77582
1 parent 052a7c7
commit 9e77582
Showing 1 changed file with 1 addition and 0 deletions.
diff --git a/XSUB.h b/XSUB.h
@@ -327,6 +327,7 @@ Rethrows a previously caught exception.  See L<perlguts/"Exception Handling">.
 #define XSRETURN(off)					\
     STMT_START {					\
 	const IV tmpXSoff = (off);			\
+	assert(tmpXSoff >= 0);\
 	PL_stack_sp = PL_stack_base + ax + (tmpXSoff - 1);	\
 	return;						\
     } STMT_END