From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753969AbXC3VJq (ORCPT ); Fri, 30 Mar 2007 17:09:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753968AbXC3VJh (ORCPT ); Fri, 30 Mar 2007 17:09:37 -0400 Received: from pentafluge.infradead.org ([213.146.154.40]:58192 "EHLO pentafluge.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753964AbXC3VJa (ORCPT ); Fri, 30 Mar 2007 17:09:30 -0400 Date: Fri, 30 Mar 2007 14:04:04 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: Justin Forbes , Zwane Mwaikambo , "Theodore Ts'o" , Randy Dunlap , Dave Jones , Chuck Wolber , Chris Wedgwood , Michael Krufky , Chuck Ebbert , torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, uml-devel , Jeff Dike Subject: [patch 05/37] UML - host VDSO fix Message-ID: <20070330210404.GF29450@kroah.com> References: <20070330205938.984247529@mini.kroah.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline; filename="uml-host-vdso-fix.patch" In-Reply-To: <20070330210334.GA29450@kroah.com> User-Agent: Mutt/1.5.14 (2007-02-12) X-Bad-Reply: References and In-Reply-To but no 'Re:' in Subject. Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org -stable review patch. If anyone has any objections, please let us know. ------------------ From: Jeff Dike This fixes a problem seen by a number of people running UML on newer host kernels. init would hang with an infinite segfault loop. It turns out that the host kernel was providing a AT_SYSINFO_EHDR of 0xffffe000, which faked UML into believing that the host VDSO page could be reused. However, AT_SYSINFO pointed into the middle of the address space, and was unmapped as a result. Because UML was providing AT_SYSINFO_EHDR and AT_SYSINFO to its own processes, these would branch to nowhere when trying to use the VDSO. The fix is to also check the location of AT_SYSINFO when deciding whether to use the host's VDSO. Signed-off-by: Jeff Dike Signed-off-by: Greg Kroah-Hartman --- arch/um/os-Linux/elf_aux.c | 3 +++ 1 file changed, 3 insertions(+) --- a/arch/um/os-Linux/elf_aux.c +++ b/arch/um/os-Linux/elf_aux.c @@ -40,6 +40,9 @@ __init void scan_elf_aux( char **envp) switch ( auxv->a_type ) { case AT_SYSINFO: __kernel_vsyscall = auxv->a_un.a_val; + /* See if the page is under TASK_SIZE */ + if (__kernel_vsyscall < (unsigned long) envp) + __kernel_vsyscall = 0; break; case AT_SYSINFO_EHDR: vsyscall_ehdr = auxv->a_un.a_val; --