Date: Wed, 20 Aug 2014 16:41:05 +0200 From: =?UTF-8?B?Um9nZXIgUGF1IE1vbm7DqQ==?= <royger@FreeBSD.org> To: Konstantin Belousov <kib@FreeBSD.org>, src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r265003 - head/secure/usr.sbin/sshd Message-ID: <53F4B381.5010205@FreeBSD.org> In-Reply-To: <201404270528.s3R5SEIm054377@svn.freebsd.org> References: <201404270528.s3R5SEIm054377@svn.freebsd.org>
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On 27/04/14 07:28, Konstantin Belousov wrote: > Author: kib > Date: Sun Apr 27 05:28:14 2014 > New Revision: 265003 > URL: http://svnweb.freebsd.org/changeset/base/265003 > > Log: > Fix order of libthr and libc in the global dso list for sshd, by > explicitely linking main binary with -lpthread. Before, libthr > appeared in the list due to dependency of one of the kerberos libs. > Due to the change in ld(1) behaviour of not copying NEEDED entries > from direct dependencies into the link results, the order becomes > reversed. > > The libthr must appear before libc to properly interpose libc symbols > and provide working rtld locks implementation. The symptom was sshd > hanging on rtld bind lock during nested symbol binding from a signal > handler. > > Approved by: des (openssh maintainer) > Sponsored by: The FreeBSD Foundation > MFC after: 1 week > > Modified: > head/secure/usr.sbin/sshd/Makefile > > Modified: head/secure/usr.sbin/sshd/Makefile > ============================================================================== > --- head/secure/usr.sbin/sshd/Makefile Sun Apr 27 05:19:01 2014 (r265002) > +++ head/secure/usr.sbin/sshd/Makefile Sun Apr 27 05:28:14 2014 (r265003) > @@ -57,6 +57,16 @@ CFLAGS+= -DNONE_CIPHER_ENABLED > DPADD+= ${LIBCRYPT} ${LIBCRYPTO} ${LIBZ} > LDADD+= -lcrypt -lcrypto -lz > > +# Fix the order of NEEDED entries for libthr and libc. The libthr > +# needs to interpose libc symbols, leaving the libthr loading as > +# dependency of krb causes reversed order and broken interposing. Put > +# the threading library last on the linker command line, just before > +# the -lc added by a compiler driver. > +.if ${MK_KERBEROS_SUPPORT} != "no" > +DPADD+= ${LIBPTHREAD} > +LDADD+= -lpthread > +.endif > + > .if defined(LOCALBASE) > CFLAGS+= -DXAUTH_PATH=\"${LOCALBASE}/bin/xauth\" > .endif Hello, This change makes the following simple test program fail on the second assert. The problem is that sa_handler == SIG_DFL, and sa_flags == SA_SIGINFO, which according to the sigaction(9) man page is not possible. With this change reverted the test is successful. --- #include <signal.h> #include <string.h> #include <assert.h> int main(int argn, char **argv) { struct sigaction new, old; int rc; memset(&new, 0, sizeof(new)); memset(&old, 0, sizeof(old)); sigemptyset(&new.sa_mask); new.sa_handler = SIG_DFL; new.sa_flags = 0; rc = sigaction(SIGCHLD, &new, &old); assert(rc == 0); assert((old.sa_handler == SIG_DFL || old.sa_handler == SIG_IGN) && !(old.sa_flags & SA_SIGINFO)); return (0); }
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