From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id ED9A9C432C0 for ; Sat, 30 Nov 2019 06:04:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B4D5E2082E for ; Sat, 30 Nov 2019 06:04:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=axtens.net header.i=@axtens.net header.b="AJPT1F66" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726924AbfK3GEw (ORCPT ); Sat, 30 Nov 2019 01:04:52 -0500 Received: from mail-pj1-f66.google.com ([209.85.216.66]:33103 "EHLO mail-pj1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725298AbfK3GEw (ORCPT ); Sat, 30 Nov 2019 01:04:52 -0500 Received: by mail-pj1-f66.google.com with SMTP id r67so6560793pjb.0 for ; Fri, 29 Nov 2019 22:04:50 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=axtens.net; s=google; h=from:to:cc:subject:in-reply-to:references:date:message-id :mime-version; bh=I+UGpdIXNr8v7drCCgj6CSr/PvndKx70EiWQ/dbfpjM=; b=AJPT1F66ZluKCDft9O1xmcX6cGgjMmH1YpFwzhc2uV+U2aIoL72Hcj4mFQEuGbBFgj ME35eTBfkK/oUnsXH4ztIE0GtBmGT+R4fyANRSK4nhH03c21U/L6uSS0KTT1WJO6Bcrn MzSia7Ub1NcnsMN6KtxAjVP4KGDx0n+mg+u44= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:in-reply-to:references:date :message-id:mime-version; bh=I+UGpdIXNr8v7drCCgj6CSr/PvndKx70EiWQ/dbfpjM=; b=pNjnMAKxRf521RLHEDOb3L/968O4OWtUpUOxxutFUKfFOzrjMCqLKw975pxGG57fvY UbPbSgZw0VK2SJF8dlcYluLtJKCiQ6oqwoaWMqSiS2vYvnJGZ75oZNLvflm8cD94Xate gCzZsRSdWxu3nPuL+JIiq+rsfbJeIeTggrOsYtOgpQ3KNwneLQtH7V0n1WwxjHxrkBEP a8ZL5SXvKrYtIo3VzxzkyZE8OP5zPBMjWFv8jhTK0bl8gRV2RpyAyvf4dZkVPmx9sxNv b6M0muNdmeYTJbbkMDyOedl/f5qTepcZKnYG6+k3VUCBC5GfMP5IU1Esv58OF337lrrl JQfw== X-Gm-Message-State: APjAAAVsQDQL5MGTsGjNvN6rOBy6RUK6TmGS6Mxkk3xtGSwKNdkqYlWN KMR8P2Mz7OJOfvvt43SmEspEWBmW7hY= X-Google-Smtp-Source: APXvYqyOz1eFIc5UhQbOZYZuFCcxy0TBGCy9INsqZnIafIclOjjhDKQ93aIMf2fAzVGYiJi4GbFbtg== X-Received: by 2002:a17:902:8498:: with SMTP id c24mr17499736plo.223.1575093890084; Fri, 29 Nov 2019 22:04:50 -0800 (PST) Received: from localhost (2001-44b8-1113-6700-4092-39f5-bb9d-b59a.static.ipv6.internode.on.net. [2001:44b8:1113:6700:4092:39f5:bb9d:b59a]) by smtp.gmail.com with ESMTPSA id o8sm12389519pjo.7.2019.11.29.22.04.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 29 Nov 2019 22:04:49 -0800 (PST) From: Daniel Axtens To: linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk Cc: akash.goel@intel.com, ajd@linux.ibm.com, syzbot+1e925b4b836afe85a1c6@syzkaller-ppc64.appspotmail.com, syzbot+587b2421926808309d21@syzkaller-ppc64.appspotmail.com, syzbot+58320b7171734bf79d26@syzkaller.appspotmail.com, syzbot+d6074fb08bdb2e010520@syzkaller.appspotmail.com Subject: Re: [PATCH] relay: handle alloc_percpu returning NULL in relay_open In-Reply-To: <20191129013745.7168-1-dja@axtens.net> References: <20191129013745.7168-1-dja@axtens.net> Date: Sat, 30 Nov 2019 17:04:45 +1100 Message-ID: <87v9r1ew76.fsf@dja-thinkpad.axtens.net> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Daniel Axtens writes: > -- > > There's a syz reproducer on the powerpc syzbot that eventually hits > the bug, but it can take up to an hour or so before it keels over on a > kernel with all the syzkaller debugging on, and even longer on a > production kernel. I have been able to reproduce it once on a stock > Ubuntu 5.0 ppc64le kernel. > > I will ask MITRE for a CVE - while only the process doing the syscall > gets killed, it gets killed while holding the relay_channels_mutex, > so it blocks all future relay activity. CVE-2019-19462 has been assigned. Regards, Daniel > --- > kernel/relay.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/kernel/relay.c b/kernel/relay.c > index ade14fb7ce2e..a376cc6b54ec 100644 > --- a/kernel/relay.c > +++ b/kernel/relay.c > @@ -580,7 +580,13 @@ struct rchan *relay_open(const char *base_filename, > if (!chan) > return NULL; > > - chan->buf = alloc_percpu(struct rchan_buf *); > + chan->buf = alloc_percpu_gfp(struct rchan_buf *, > + GFP_KERNEL | __GFP_NOWARN); > + if (!chan->buf) { > + kfree(chan); > + return NULL; > + } > + > chan->version = RELAYFS_CHANNEL_VERSION; > chan->n_subbufs = n_subbufs; > chan->subbuf_size = subbuf_size; > -- > 2.20.1