From 9e77582c6bb40536b9ca4037729a9b0f2c7ff932 Mon Sep 17 00:00:00 2001
From: Doug Bell <madcityzen@gmail.com>
Date: Tue, 2 Jun 2015 22:34:42 -0500
Subject: add assertion to prevent stack corruption in XSUB

We should not be able to return negative offsets from the stack in
XSUBs.
---
 XSUB.h | 1 +
 1 file changed, 1 insertion(+)

(limited to 'XSUB.h')

diff --git a/XSUB.h b/XSUB.h
index 4548fc99b8..e64bc83b92 100644
--- 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
-- 
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