From a94a4b74bdd9f9fa2cd9ec7f782fd6ed394e76ab Mon Sep 17 00:00:00 2001
From: Mark Johnston <markj@FreeBSD.org>
Date: Wed, 7 Aug 2013 00:28:17 +0000
Subject: [PATCH] Pass variables prefixed with both LD_ and LD_32_ to the
 run-time linker. This prevents unintentional execution of programs when
 running ldd(1) on 32-bit Linux binaries.

PR:		175339, 127276
Suggested by:	kib, rstone
Reviewed by:	kib
MFC after:	2 weeks
---
 usr.bin/ldd/ldd.c | 30 +++++++++++++++++-------------
 1 file changed, 17 insertions(+), 13 deletions(-)

diff --git a/usr.bin/ldd/ldd.c b/usr.bin/ldd/ldd.c
index 00c87975d854..bc4dbb6204ae 100644
--- a/usr.bin/ldd/ldd.c
+++ b/usr.bin/ldd/ldd.c
@@ -49,12 +49,6 @@ __FBSDID("$FreeBSD$");
 
 #include "extern.h"
 
-#ifdef COMPAT_32BIT
-#define	LD_	"LD_32_"
-#else
-#define	LD_	"LD_"
-#endif
-
 /*
  * 32-bit ELF data structures can only be used if the system header[s] declare
  * them.  There is no official macro for determining whether they are declared,
@@ -64,6 +58,16 @@ __FBSDID("$FreeBSD$");
 #define	ELF32_SUPPORTED
 #endif
 
+#define	LDD_SETENV(name, value, overwrite) do {		\
+	setenv("LD_" name, value, overwrite);		\
+	setenv("LD_32_" name, value, overwrite);	\
+} while (0)
+
+#define	LDD_UNSETENV(name) do {		\
+	unsetenv("LD_" name);		\
+	unsetenv("LD_32_" name);	\
+} while (0)
+
 static int	is_executable(const char *fname, int fd, int *is_shlib,
 		    int *type);
 static void	usage(void);
@@ -82,7 +86,7 @@ execldd32(char *file, char *fmt1, char *fmt2, int aflag, int vflag)
 	char *argv[8];
 	int i, rval, status;
 
-	unsetenv(LD_ "TRACE_LOADED_OBJECTS");
+	LDD_UNSETENV("TRACE_LOADED_OBJECTS");
 	rval = 0;
 	i = 0;
 	argv[i++] = strdup(_PATH_LDD32);
@@ -121,7 +125,7 @@ execldd32(char *file, char *fmt1, char *fmt2, int aflag, int vflag)
 	}
 	while (i--)
 		free(argv[i]);
-	setenv(LD_ "TRACE_LOADED_OBJECTS", "yes", 1);
+	LDD_SETENV("TRACE_LOADED_OBJECTS", "yes", 1);
 	return (rval);
 }
 #endif
@@ -210,15 +214,15 @@ main(int argc, char *argv[])
 		}
 
 		/* ld.so magic */
-		setenv(LD_ "TRACE_LOADED_OBJECTS", "yes", 1);
+		LDD_SETENV("TRACE_LOADED_OBJECTS", "yes", 1);
 		if (fmt1 != NULL)
-			setenv(LD_ "TRACE_LOADED_OBJECTS_FMT1", fmt1, 1);
+			LDD_SETENV("TRACE_LOADED_OBJECTS_FMT1", fmt1, 1);
 		if (fmt2 != NULL)
-			setenv(LD_ "TRACE_LOADED_OBJECTS_FMT2", fmt2, 1);
+			LDD_SETENV("TRACE_LOADED_OBJECTS_FMT2", fmt2, 1);
 
-		setenv(LD_ "TRACE_LOADED_OBJECTS_PROGNAME", *argv, 1);
+		LDD_SETENV("TRACE_LOADED_OBJECTS_PROGNAME", *argv, 1);
 		if (aflag)
-			setenv(LD_ "TRACE_LOADED_OBJECTS_ALL", "1", 1);
+			LDD_SETENV("TRACE_LOADED_OBJECTS_ALL", "1", 1);
 		else if (fmt1 == NULL && fmt2 == NULL)
 			/* Default formats */
 			printf("%s:\n", *argv);