From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yann E. MORIN Date: Sun, 13 Aug 2017 14:56:06 +0200 Subject: [Buildroot] [PATCH/2017.02.x 2/2] dbus: add upstream patch to fix startup hang with with expat >= 2.2.1 In-Reply-To: <1502372823-31706-2-git-send-email-sebastien.szymanski@armadeus.com> References: <1502372823-31706-1-git-send-email-sebastien.szymanski@armadeus.com> <1502372823-31706-2-git-send-email-sebastien.szymanski@armadeus.com> Message-ID: <20170813125606.GA3475@scaer> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: buildroot@busybox.net S?bastien, All, On 2017-08-10 15:47 +0200, S?bastien Szymanski spake thusly: > From: Marcus Hoffmann > After c0ad6ded018ffbc33f7f5 expat: security bump to version 2.2.1 > the system can hang on startup under certain circumstances. > > This happens when: > * we use systemd as init system > * the random nonblocking pool takes a while to initialize > * this apparently doesn't happen on qemu, so this would not have > been caught by the runtime testing infrastructure > * it also doesn't seem to happen when network booting > > For a more detailed description of the bug see here: > https://bugs.freedesktop.org/show_bug.cgi?id=101858 > > The patch should be in next dbus version 1.10.24 In the meantime. expat 2.2.3 has been released, which contrains (amongst other interesting stuff) commit 55839b633 (xmlparse.c: Read /dev/urandom if non-blocking getrandom failed), which ought to fix the boot delay. So, maybe it is beter to bumnpt expat instead, no? Or at least, backport that one commit. Or did I miss something? Regards, Yann E. MORIN. > Set DBUS_AUTORECONF = YES because configure.ac is changed. > > Signed-off-by: Marcus Hoffmann > [Arnout: add upstream commit sha + Marcus's Sob to the patch] > Signed-off-by: Arnout Vandecappelle (Essensium/Mind) > > (cherry picked from commit 5a5e76381f8b000baa09c902ca89d45725c47f04) > Signed-off-by: S?bastien Szymanski > --- > ...er-expat-Tell-Expat-not-to-defend-against.patch | 78 ++++++++++++++++++++++ > package/dbus/dbus.mk | 3 + > 2 files changed, 81 insertions(+) > create mode 100644 package/dbus/0001-config-loader-expat-Tell-Expat-not-to-defend-against.patch > > diff --git a/package/dbus/0001-config-loader-expat-Tell-Expat-not-to-defend-against.patch b/package/dbus/0001-config-loader-expat-Tell-Expat-not-to-defend-against.patch > new file mode 100644 > index 0000000..fd9e01d > --- /dev/null > +++ b/package/dbus/0001-config-loader-expat-Tell-Expat-not-to-defend-against.patch > @@ -0,0 +1,78 @@ > +From 1252dc1d1f465b8ab6b36ff7252e395e66a040cf Mon Sep 17 00:00:00 2001 > +From: Simon McVittie > +Date: Fri, 21 Jul 2017 10:46:39 +0100 > +Subject: [PATCH 1/2] config-loader-expat: Tell Expat not to defend against > + hash collisions > + > +By default, Expat uses cryptographic-quality random numbers as a salt for > +its hash algorithm, and since 2.2.1 it gets them from the getrandom > +syscall on Linux. That syscall refuses to return any entropy until the > +kernel's CSPRNG (random pool) has been initialized. Unfortunately, this > +can take as long as 40 seconds on embedded devices with few entropy > +sources, which is too long: if the system dbus-daemon blocks for that > +length of time, important D-Bus clients like systemd and systemd-logind > +time out and fail to connect to it. > + > +We're parsing small configuration files here, and we trust them > +completely, so we don't need to defend against hash collisions: nobody > +is going to be crafting them to cause pathological performance. > + > +Bug: https://bugs.freedesktop.org/show_bug.cgi?id=101858 > +Signed-off-by: Simon McVittie > +Tested-by: Christopher Hewitt > +Reviewed-by: Philip Withnall > + > +Upstream commit 1252dc1d1f465b8ab6b36ff7252e395e66a040cf > +Signed-off-by: Marcus Hoffmann > +--- > + bus/config-loader-expat.c | 14 ++++++++++++++ > + configure.ac | 8 ++++++++ > + 2 files changed, 22 insertions(+) > + > +diff --git a/bus/config-loader-expat.c b/bus/config-loader-expat.c > +index b571fda3..27cbe2d0 100644 > +--- a/bus/config-loader-expat.c > ++++ b/bus/config-loader-expat.c > +@@ -203,6 +203,20 @@ bus_config_load (const DBusString *file, > + goto failed; > + } > + > ++ /* We do not need protection against hash collisions (CVE-2012-0876) > ++ * because we are only parsing trusted XML; and if we let Expat block > ++ * waiting for the CSPRNG to be initialized, as it does by default to > ++ * defeat CVE-2012-0876, it can cause timeouts during early boot on > ++ * entropy-starved embedded devices. > ++ * > ++ * TODO: When Expat gets a more explicit API for this than > ++ * XML_SetHashSalt, check for that too, and use it preferentially. > ++ * https://github.com/libexpat/libexpat/issues/91 */ > ++#if defined(HAVE_XML_SETHASHSALT) > ++ /* Any nonzero number will do. https://xkcd.com/221/ */ > ++ XML_SetHashSalt (expat, 4); > ++#endif > ++ > + if (!_dbus_string_get_dirname (file, &dirname)) > + { > + dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL); > +diff --git a/configure.ac b/configure.ac > +index 52da11fb..c4022ed7 100644 > +--- a/configure.ac > ++++ b/configure.ac > +@@ -938,6 +938,14 @@ XML_CFLAGS= > + AC_SUBST([XML_CFLAGS]) > + AC_SUBST([XML_LIBS]) > + > ++save_cflags="$CFLAGS" > ++save_libs="$LIBS" > ++CFLAGS="$CFLAGS $XML_CFLAGS" > ++LIBS="$LIBS $XML_LIBS" > ++AC_CHECK_FUNCS([XML_SetHashSalt]) > ++CFLAGS="$save_cflags" > ++LIBS="$save_libs" > ++ > + # Thread lib detection > + AC_ARG_VAR([THREAD_LIBS]) > + save_libs="$LIBS" > +-- > +2.11.0 > + > diff --git a/package/dbus/dbus.mk b/package/dbus/dbus.mk > index e05fbff..f2974f2 100644 > --- a/package/dbus/dbus.mk > +++ b/package/dbus/dbus.mk > @@ -6,6 +6,9 @@ > > DBUS_VERSION = 1.10.22 > DBUS_SITE = https://dbus.freedesktop.org/releases/dbus > + > +# 0001-config-loader-expat-Tell-Expat-not-to-defend-against.patch > +DBUS_AUTORECONF = YES > DBUS_LICENSE = AFLv2.1 or GPLv2+ (library, tools), GPLv2+ (tools) > DBUS_LICENSE_FILES = COPYING > DBUS_INSTALL_STAGING = YES > -- > 2.7.3 > > _______________________________________________ > buildroot mailing list > buildroot at busybox.net > http://lists.busybox.net/mailman/listinfo/buildroot -- .-----------------.--------------------.------------------.--------------------. | Yann E. 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