From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756826AbZBDUdN (ORCPT ); Wed, 4 Feb 2009 15:33:13 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753240AbZBDUc5 (ORCPT ); Wed, 4 Feb 2009 15:32:57 -0500 Received: from monty.telenet-ops.be ([195.130.132.56]:55726 "EHLO monty.telenet-ops.be" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752673AbZBDUc4 (ORCPT ); Wed, 4 Feb 2009 15:32:56 -0500 Date: Wed, 4 Feb 2009 21:32:51 +0100 (CET) From: Geert Uytterhoeven To: Shane Hathaway , Heiko Carstens , Greg Kroah-Hartman cc: Daolong Wang , User-mode Linux Kernel Development , Jeff Dike , Linux Kernel Development , Rob Landley , Am?rico Wang , Andrew Morton , stable@kernel.org, Geert Uytterhoeven Subject: Re: [uml-devel] [Patch] uml: fix a link error In-Reply-To: Message-ID: References: <20090115194033.GA10926@hack.private> <20090116124158.4364e269.akpm@linux-foundation.org> <200901170328.15178.rob@landley.net> <20090119152104.GC6432@c2.user-mode-linux.org> <49753063.8040007@hathawaymix.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 4 Feb 2009, Geert Uytterhoeven wrote: > On Mon, 19 Jan 2009, Shane Hathaway wrote: > > Daolong Wang wrote: > > > On Mon, Jan 19, 2009 at 11:21 PM, Jeff Dike wrote: > > >> On Sun, Jan 18, 2009 at 02:23:46PM +0800, Daolong Wang wrote: > > >>> I can confirm this link error. > > >> In what environment? I see no problems here. > > > > I can also confirm this link error. The problem occurs when compiling > > either 2.6.28.1 or 2.6.27.12; I didn't try anything earlier. The patch > > suggested at this beginning of this thread did solve the link problem > > and the resulting kernel ran for several hours. However, I think the > > patch is still probably incorrect. > > > > I'm going to repost what I said in another message I sent today, this > > time with a wider audience: > > > > The problem is that the name "sigprocmask" is getting renamed to > > "kernel_sigprocmask" by a compiler directive in arch/um/Makefile, then > > that name gets mangled into "sys_kernel_sigprocmask" by the > > SYSCALL_DEFINE3(sigprocmask, ...) macro in kernel/signal.c. > > > > So, instead of the patch suggested earlier, I added the following line > > to arch/um/sys-i386/sys_call_table.S: > > > > #define sys_sigprocmask sys_kernel_sigprocmask > > > > This made it compile and link correctly. Look at the symbols generated > > by the compile of signal.c to see what I mean: > > > > # nm kernel/signal.o | grep sigprocmask > > 0000008f r __kstrtab_kernel_sigprocmask > > 00000040 r __ksymtab_kernel_sigprocmask > > 00001ea6 T kernel_sigprocmask > > 00002d67 T sys_kernel_sigprocmask > > 00001faf T sys_rt_sigprocmask > > > > Unfortunately, it's a mystery to me that others haven't run into this > > before. My host environment is RHEL 4 inside some kind of chroot. > > I've just started seeing this problem with some 2.6.29-rc3 kernel... > > Before, I did not have this problem with various 2.6.28-rc8 and 2.6.29-rc1 > kernels (and several older versions I don't remember). > > Given 2.6.29-rc1 works for me and 2.6.28.1 fails for you, I'm inclined to > believe 2.6.28 is OK. I'll give it a try... > > BTW, I'm using CentOS 5.2. Following up from home... Indeed, 2.6.28 works, 2.6.28.1 doesn't. According to git bisect, it got introduced by the system call security fixes (CVE-2009-0029), more specifically by this part: | commit fe7c0d987fb2cce464d29eec9dfcca6296b5eed7 | Author: Heiko Carstens | Date: Wed Jan 14 14:14:06 2009 +0100 | | System call wrappers part 04 | | commit b290ebe2c46d01b742b948ce03f09e8a3efb9a92 upstream. | | Signed-off-by: Heiko Carstens | Signed-off-by: Greg Kroah-Hartman | | --- a/kernel/signal.c | +++ b/kernel/signal.c | @@ -2425,8 +2424,8 @@ sys_sigpending(old_sigset_t __user *set) | /* Some platforms have their own version with special arguments others | support only sys_rt_sigprocmask. */ | | -asmlinkage long | -sys_sigprocmask(int how, old_sigset_t __user *set, old_sigset_t __user *oset) ^^^^^^^^^^^^^^^ | +SYSCALL_DEFINE3(sigprocmask, int, how, old_sigset_t __user *, set, ^^^^^^^^^^^ | + old_sigset_t __user *, oset) | { | int error; | old_sigset_t old_set, new_set; Hence it allows sigprocmask to be redefined to kernel_sigprocmask by the C preprocessor... This got backported to 2.6.27.12 as well, confusing people who ran post-2.6.27 development kernels and never noticed the problem (including Jeff and me)... It showed up in a "development" kernel in 2.6.29-rc2 only. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds