From 84200b423ebfa7e2dad9b1b65f64eac7bf3d2114 Mon Sep 17 00:00:00 2001
From: Diego Elio 'Flameeyes' Pettenò <flameeyes@gmail.com>
Date: Tue, 7 Jul 2009 20:51:53 +0200
Subject: Remove exploitable LD_BIND_NOW hack (CVE-2009-1894).

Instead of trying to re-execute pulseaudio itself with LD_BIND_NOW set,
just find the correct flag for the linker to request immediate bindings
(all ELF files support that option), and use that when linking the daemon.

Reduce the amount of compiled and executed code as well.
---
 configure.ac      |  6 ++++++
 src/Makefile.am   |  4 ++--
 src/daemon/main.c | 22 ----------------------
 3 files changed, 8 insertions(+), 24 deletions(-)

diff --git a/configure.ac b/configure.ac
index 9c96d1c5..cc7f674a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -113,6 +113,12 @@ CC_CHECK_LDFLAGS([${tmp_ldflag}],
     [VERSIONING_LDFLAGS='-Wl,-version-script=$(srcdir)/map-file'])
 AC_SUBST([VERSIONING_LDFLAGS])
 
+dnl Use immediate (now) bindings; avoids the funky re-call in itself
+dnl  the -z now syntax is lifted from Sun's linker and works with GNU's too
+dnl  other linkes might be added later
+CC_CHECK_LDFLAGS([-Wl,-z,now], [IMMEDIATE_LDFLAGS="-Wl,-z,now"])
+AC_SUBST([IMMEDIATE_LDFLAGS])
+
 dnl Check for the proper way to build libraries that have no undefined
 dnl symbols; on some hosts this needs to be avoided but the macro
 dnl takes care of it.
diff --git a/src/Makefile.am b/src/Makefile.am
index 7ebf1f8a..ac627c84 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -183,9 +183,9 @@ PREOPEN_LIBS = $(modlibexec_LTLIBRARIES)
 endif
 
 if FORCE_PREOPEN
-pulseaudio_LDFLAGS = $(AM_LDFLAGS) $(BINLDFLAGS) -dlpreopen force $(foreach f,$(PREOPEN_LIBS),-dlpreopen $(f))
+pulseaudio_LDFLAGS = $(AM_LDFLAGS) $(BINLDFLAGS) $(IMMEDIATE_LDFLAGS) -dlpreopen force $(foreach f,$(PREOPEN_LIBS),-dlpreopen $(f))
 else
-pulseaudio_LDFLAGS = $(AM_LDFLAGS) $(BINLDFLAGS) -dlopen force $(foreach f,$(PREOPEN_LIBS),-dlopen $(f))
+pulseaudio_LDFLAGS = $(AM_LDFLAGS) $(BINLDFLAGS) $(IMMEDIATE_LDFLAGS) -dlopen force $(foreach f,$(PREOPEN_LIBS),-dlopen $(f))
 endif
 
 ###################################
diff --git a/src/daemon/main.c b/src/daemon/main.c
index eb378d24..0f6fc907 100644
--- a/src/daemon/main.c
+++ b/src/daemon/main.c
@@ -401,28 +401,6 @@ int main(int argc, char *argv[]) {
     pa_log_set_level(PA_LOG_NOTICE);
     pa_log_set_flags(PA_LOG_COLORS|PA_LOG_PRINT_FILE|PA_LOG_PRINT_LEVEL, PA_LOG_RESET);
 
-#if defined(__linux__) && defined(__OPTIMIZE__)
-    /*
-       Disable lazy relocations to make usage of external libraries
-       more deterministic for our RT threads. We abuse __OPTIMIZE__ as
-       a check whether we are a debug build or not.
-    */
-
-    if (!getenv("LD_BIND_NOW")) {
-        char *rp;
-
-        /* We have to execute ourselves, because the libc caches the
-         * value of $LD_BIND_NOW on initialization. */
-
-        pa_set_env("LD_BIND_NOW", "1");
-
-        if ((rp = pa_readlink("/proc/self/exe")))
-            pa_assert_se(execv(rp, argv) == 0);
-        else
-            pa_log_warn("Couldn't read /proc/self/exe, cannot self execute. Running in a chroot()?");
-    }
-#endif
-
     if ((e = getenv("PULSE_PASSED_FD"))) {
         passed_fd = atoi(e);
 
-- 
cgit