From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp.tuxdriver.com (charlotte.tuxdriver.com [70.61.120.58]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mail09.linbit.com (LINBIT Mail Daemon) with ESMTPS id 186641011BEC for ; Sun, 31 Jan 2010 18:42:09 +0100 (CET) Date: Sun, 31 Jan 2010 12:41:48 -0500 From: Neil Horman To: Oleg Nesterov Message-ID: <20100131160030.GB1950@localhost.localdomain> References: <20100121200806.GA29801@shamino.rdu.redhat.com> <20100129151024.GA19249@hmsreliant.think-freely.org> <20100129151458.GC19249@hmsreliant.think-freely.org> <20100131155000.GB13402@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100131155000.GB13402@redhat.com> Cc: jmoskovc@redhat.com, neilb@suse.de, benh@kernel.crashing.org, gregkh@suse.de, takedakn@nttdata.co.jp, linux-kernel@vger.kernel.org, spock@gentoo.org, mingo@redhat.com, viro@zeniv.linux.org.uk, mfasheh@suse.com, akpm@linux-foundation.org, t.sailer@alumni.ethz.ch, shemminger@linux-foundation.org, menage@google.com, abelay@mit.edu, drbd-dev@lists.linbit.com Subject: Re: [Drbd-dev] [PATCH 2/2] exec: allow core_pipe recursion check to look for a value of 1 rather than 0 (v2) List-Id: Coordination of development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Sun, Jan 31, 2010 at 04:50:01PM +0100, Oleg Nesterov wrote: > On 01/29, Neil Horman wrote: > > > > void do_coredump(long signr, int exit_code, struct pt_regs *regs) > > { > > ... > > - if (call_usermodehelper_pipe(helper_argv[0], helper_argv, NULL, > > - &cprm.file)) { > > + cprm.file = NULL; > > it is already NULL, > Are we sure, it was declared on the stack. I think its safer to ensure that its NULL. > > + if (call_usermodehelper_fns(helper_argv[0], helper_argv, NULL, > > + UMH_WAIT_EXEC, umh_pipe_setup, > > + NULL, &cprm)) { > > + if (cprm.file) > > + filp_close(cprm.file, NULL); > > Hmm. Looks like this change fixes the bug by accident. > > Before this patch, I think we leak info->stdin if kernel_thread() fails > in __call_usermodehelper() pathes. > I think we did that in call_usermodehelper_pipe. > > > Completely off-topic, but I think __call_usermodehelper(UMH_NO_WAIT) is > buggy. if kernel_thread() failes it should do call_usermodehelper_freeinfo(). > Also, UMH_WAIT_EXEC should set ->retval in this case. > I went down that path last time I changed this code, Andrew and I decided that yes it was buggy, but someone (can't recall how) smacked me around a bit and explained how it worked (some odd artifact behavior of the scheduler). Its in the lkml archives if you want to get the whole story. > Cough. And why call_usermodehelper_exec() has this strange ->path[0] == '\0' > check? > That I can't explain. I figured I'd let that sleeping dog lie until this got striaghtened out and fix it separately if it needed it Neil > Oleg. > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ >