svn commit: r265003 - head/secure/usr.sbin/sshd

[Roger Pau Monné]

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);
}