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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 1CFC9C48BE5 for ; Tue, 15 Jun 2021 05:32:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DEAE06140C for ; Tue, 15 Jun 2021 05:32:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230215AbhFOFeO (ORCPT ); Tue, 15 Jun 2021 01:34:14 -0400 Received: from helcar.hmeau.com ([216.24.177.18]:50658 "EHLO deadmen.hmeau.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230038AbhFOFeN (ORCPT ); Tue, 15 Jun 2021 01:34:13 -0400 Received: from gondobar.mordor.me.apana.org.au ([192.168.128.4] helo=gondobar) by deadmen.hmeau.com with esmtp (Exim 4.92 #5 (Debian)) id 1lt1gD-0006u3-8A; Tue, 15 Jun 2021 13:32:05 +0800 Received: from herbert by gondobar with local (Exim 4.92) (envelope-from ) id 1lt1g7-0001R0-Bs; Tue, 15 Jun 2021 13:31:59 +0800 Date: Tue, 15 Jun 2021 13:31:59 +0800 From: Herbert Xu To: syzbot Cc: davem@davemloft.net, kuba@kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, steffen.klassert@secunet.com, syzkaller-bugs@googlegroups.com Subject: Re: [syzbot] UBSAN: shift-out-of-bounds in xfrm_selector_match Message-ID: <20210615053159.GA5412@gondor.apana.org.au> References: <000000000000008a6c05c46e45a4@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <000000000000008a6c05c46e45a4@google.com> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jun 10, 2021 at 12:19:26PM -0700, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: 13c62f53 net/sched: act_ct: handle DNAT tuple collision > git tree: net > console output: https://syzkaller.appspot.com/x/log.txt?x=16635470300000 > kernel config: https://syzkaller.appspot.com/x/.config?x=770708ea7cfd4916 > dashboard link: https://syzkaller.appspot.com/bug?extid=e4c1dd36fc6b98c50859 > > Unfortunately, I don't have any reproducer for this issue yet. > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+e4c1dd36fc6b98c50859@syzkaller.appspotmail.com > > UBSAN: shift-out-of-bounds in ./include/net/xfrm.h:838:23 > shift exponent -64 is negative > CPU: 0 PID: 12625 Comm: syz-executor.1 Not tainted 5.13.0-rc3-syzkaller #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > Call Trace: > __dump_stack lib/dump_stack.c:79 [inline] > dump_stack+0x141/0x1d7 lib/dump_stack.c:120 > ubsan_epilogue+0xb/0x5a lib/ubsan.c:148 > __ubsan_handle_shift_out_of_bounds.cold+0xb1/0x181 lib/ubsan.c:327 > addr4_match include/net/xfrm.h:838 [inline] > __xfrm4_selector_match net/xfrm/xfrm_policy.c:201 [inline] > xfrm_selector_match.cold+0x35/0x3a net/xfrm/xfrm_policy.c:227 > xfrm_state_look_at+0x16d/0x440 net/xfrm/xfrm_state.c:1022 This appears to be an xfrm_state object with an IPv4 selector that somehow has a prefixlen (d or s) of 96. AFAICS this is not possible through xfrm_user. OTOH it is not obvious that af_key is entirely consistent in how it verifies the prefix length, in particular, it seems to be possible for two addresses with conflicting families to be provided as src/dst. Can you confirm that this is indeed using af_key (a quick read of the syzbot log seems to indicate that this is the case)? Thanks, -- Email: Herbert Xu Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt