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=-8.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_MUTT autolearn=ham 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 D429CC282CE for ; Tue, 4 Jun 2019 20:59:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 913C52075B for ; Tue, 4 Jun 2019 20:59:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="ZDyFWF8d" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726463AbfFDU7L (ORCPT ); Tue, 4 Jun 2019 16:59:11 -0400 Received: from mail-qt1-f194.google.com ([209.85.160.194]:45302 "EHLO mail-qt1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726179AbfFDU7K (ORCPT ); Tue, 4 Jun 2019 16:59:10 -0400 Received: by mail-qt1-f194.google.com with SMTP id j19so11807351qtr.12; Tue, 04 Jun 2019 13:59:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=95VaE1yZ4HFrCDRjLl3wm2mqMtFb1b8GVww8N/pHq/Y=; b=ZDyFWF8dI514ndd7WBMQROZxA01rOIaIkorX4/V++2AzWilB3owllgrxdNS1lxu3RF VQ4nkPUQTK0mUr5HsKvQ8qiU7v721QgMSSZeK+blTM0RD2Y0uMrcyLdEuJKRVfGzV33l RcUKKwVyhAYzrPHRuPbe43LBohAqVz8IZHqXe0LmTjD0Z7fcI9/XVReu3BEyAC09F29L dqZM55OP9Mnkqovn750Y6RnOaLCOnRgR+XTu8/5M550yWJc4KHOPe3AJqa7l7i1AA6Zd ZesJXjPzLEo5ppp8CUHFb/ovlESlaOTobix1jNdSt85fnXK4sD1t208cbcl5nIcfrk1+ j6wA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=95VaE1yZ4HFrCDRjLl3wm2mqMtFb1b8GVww8N/pHq/Y=; b=h8VPcAXW8lkT4b4jiBoPAEbxAMzOy+1+nc1oLmYCgjfEEzwqTdWk4X1nLAF58be+Fy +n2D4Z8LbFc4y6j3OXCz+6iAVVFa/VvSTzfOs16c3TFVwXdKEDWlMyI4V5hUssUAeL8e vbcGvryqx4Fn1K3sm8d+GpDyl5diTi5gUA5H+lCkSSCr4ef3CUe0VKM74mWFirLHQ6VI bG866odmtfdo6JOa10RWQoP8yab7JG/lm5JeKFB0IzPeSN+/u+9QcIDRwgtBPzrxN026 ZtoilCokuiTx7fNjkLjoKc3gpZRMOezJ6Ra3MEYqL3TphwxjFHdU++k18zDlKj/mrsAQ AlZw== X-Gm-Message-State: APjAAAUa7LNLNc0S7qdAOtE2DGEhZEwqKAlT2mUdqzYzXYcwlcQNi7M4 I0feLmZtpdZp2KYj6y9b/+E= X-Google-Smtp-Source: APXvYqwnUbEkVBq8nHXtHEFqTLNCA9f/PFJpgPYIeUCdaKLV+qS1DQeSwZpj+mpAFMNyJtwX1cVX8g== X-Received: by 2002:ad4:536b:: with SMTP id e11mr27110722qvv.163.1559681948613; Tue, 04 Jun 2019 13:59:08 -0700 (PDT) Received: from localhost.localdomain ([168.181.49.32]) by smtp.gmail.com with ESMTPSA id i123sm10532781qkd.32.2019.06.04.13.59.07 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 04 Jun 2019 13:59:07 -0700 (PDT) Received: by localhost.localdomain (Postfix, from userid 1000) id C5006C0879; Tue, 4 Jun 2019 17:59:04 -0300 (-03) Date: Tue, 4 Jun 2019 17:59:04 -0300 From: Marcelo Ricardo Leitner To: Xin Long Cc: Neil Horman , linux-sctp@vger.kernel.org, syzbot+f7e9153b037eac9b1df8@syzkaller.appspotmail.com, "David S. Miller" , network dev Subject: Re: [PATCH V2] Fix memory leak in sctp_process_init Message-ID: <20190604205904.GA3778@localhost.localdomain> References: <00000000000097abb90589e804fd@google.com> <20190603203259.21508-1-nhorman@tuxdriver.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.11.4 (2019-03-13) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Wed, Jun 05, 2019 at 04:16:24AM +0800, Xin Long wrote: > On Tue, Jun 4, 2019 at 4:34 AM Neil Horman wrote: > > > > syzbot found the following leak in sctp_process_init > > BUG: memory leak > > unreferenced object 0xffff88810ef68400 (size 1024): > > comm "syz-executor273", pid 7046, jiffies 4294945598 (age 28.770s) > > hex dump (first 32 bytes): > > 1d de 28 8d de 0b 1b e3 b5 c2 f9 68 fd 1a 97 25 ..(........h...% > > 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ > > backtrace: > > [<00000000a02cebbd>] kmemleak_alloc_recursive include/linux/kmemleak.h:55 > > [inline] > > [<00000000a02cebbd>] slab_post_alloc_hook mm/slab.h:439 [inline] > > [<00000000a02cebbd>] slab_alloc mm/slab.c:3326 [inline] > > [<00000000a02cebbd>] __do_kmalloc mm/slab.c:3658 [inline] > > [<00000000a02cebbd>] __kmalloc_track_caller+0x15d/0x2c0 mm/slab.c:3675 > > [<000000009e6245e6>] kmemdup+0x27/0x60 mm/util.c:119 > > [<00000000dfdc5d2d>] kmemdup include/linux/string.h:432 [inline] > > [<00000000dfdc5d2d>] sctp_process_init+0xa7e/0xc20 > > net/sctp/sm_make_chunk.c:2437 > > [<00000000b58b62f8>] sctp_cmd_process_init net/sctp/sm_sideeffect.c:682 > > [inline] > > [<00000000b58b62f8>] sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1384 > > [inline] > > [<00000000b58b62f8>] sctp_side_effects net/sctp/sm_sideeffect.c:1194 > > [inline] > > [<00000000b58b62f8>] sctp_do_sm+0xbdc/0x1d60 net/sctp/sm_sideeffect.c:1165 > > [<0000000044e11f96>] sctp_assoc_bh_rcv+0x13c/0x200 > > net/sctp/associola.c:1074 > > [<00000000ec43804d>] sctp_inq_push+0x7f/0xb0 net/sctp/inqueue.c:95 > > [<00000000726aa954>] sctp_backlog_rcv+0x5e/0x2a0 net/sctp/input.c:354 > > [<00000000d9e249a8>] sk_backlog_rcv include/net/sock.h:950 [inline] > > [<00000000d9e249a8>] __release_sock+0xab/0x110 net/core/sock.c:2418 > > [<00000000acae44fa>] release_sock+0x37/0xd0 net/core/sock.c:2934 > > [<00000000963cc9ae>] sctp_sendmsg+0x2c0/0x990 net/sctp/socket.c:2122 > > [<00000000a7fc7565>] inet_sendmsg+0x64/0x120 net/ipv4/af_inet.c:802 > > [<00000000b732cbd3>] sock_sendmsg_nosec net/socket.c:652 [inline] > > [<00000000b732cbd3>] sock_sendmsg+0x54/0x70 net/socket.c:671 > > [<00000000274c57ab>] ___sys_sendmsg+0x393/0x3c0 net/socket.c:2292 > > [<000000008252aedb>] __sys_sendmsg+0x80/0xf0 net/socket.c:2330 > > [<00000000f7bf23d1>] __do_sys_sendmsg net/socket.c:2339 [inline] > > [<00000000f7bf23d1>] __se_sys_sendmsg net/socket.c:2337 [inline] > > [<00000000f7bf23d1>] __x64_sys_sendmsg+0x23/0x30 net/socket.c:2337 > > [<00000000a8b4131f>] do_syscall_64+0x76/0x1a0 arch/x86/entry/common.c:3 > > > > The problem was that the peer.cookie value points to an skb allocated > > area on the first pass through this function, at which point it is > > overwritten with a heap allocated value, but in certain cases, where a > > COOKIE_ECHO chunk is included in the packet, a second pass through > > sctp_process_init is made, where the cookie value is re-allocated, > > leaking the first allocation. > This's not gonna happen, as after processing INIT, the temp asoc will be > deleted on the server side. Besides, from the reproducer: > > https://syzkaller.appspot.com/x/repro.syz?x=10e32f8ca00000 > > Packet(INIT|COOKIE_ECHO) can't be made in here. > > The call trace says the leak happened when processing INIT_ACK on the > client side, as Marcelo noticed. Then it can be triggered by: > > 1. sctp_sf_do_5_1C_ack() -> SCTP_CMD_PEER_INIT -> sctp_process_init(): > where it "goto clean_up" after sctp_process_param(), but in 'cleanup' > path, it doesn't do any freeup for the memdups of sctp_process_param(). > then the client T1 retrans INIT, and later get INIT_ACK again from the > peer, and go to sctp_process_init() to memdup(). > > 2. sctp_sf_cookie_echoed_err() -> sctp_sf_do_5_2_6_stale(): > where the asoc state will go from COOKIE_ECHOED back to COOKIE_WAIT, > and T1 starts to retrans INIT, and later it will get INIT_ACK again > to sctp_process_init() and memdup(). > > As on either above, asoc's never been to ESTABLISHED state, > asoc->peer.cookie can be not freed, and this patch won't work. > But yes, it's nice to have this patch, just not to fix this memleak. > > I tracked the code, this memleak was triggered by case 2, so I think > you also need to add something like: Interesting, because as part of writing some scripts here to more easily work with syzkaller reports, I actually had the patch Neil posted being tested on Friday and with it applied the reproducer didn't catch any leaks anymore, while with it, it takes a while but the leaks were happening. (Will read the details you posted later, I'm just sharing this for now, sorry for the rushiness) > > @@ -881,6 +893,18 @@ static void sctp_cmd_new_state(struct sctp_cmd_seq *cmds, > asoc->rto_initial; > asoc->timeouts[SCTP_EVENT_TIMEOUT_T1_COOKIE] = > asoc->rto_initial; > + > + if (asoc->peer.cookie) { > + kfree(asoc->peer.cookie); > + kfree(asoc->peer.peer_random); > + kfree(asoc->peer.peer_chunks); > + kfree(asoc->peer.peer_hmacs); > + > + asoc->peer.cookie = NULL; > + asoc->peer.peer_random = NULL; > + asoc->peer.peer_random = NULL; > + asoc->peer.peer_hmacs = NULL; > + } > } > > and the same thing may also be needed in sctp_cmd_process_init() on the > err path for case 1. > > > > > Fix is to always allocate the cookie value, and free it when we are done > > using it. > > > > Signed-off-by: Neil Horman > > Reported-by: syzbot+f7e9153b037eac9b1df8@syzkaller.appspotmail.com > > CC: Marcelo Ricardo Leitner > > CC: "David S. Miller" > > CC: netdev@vger.kernel.org > > > > --- > > Change notes > > > > V1->V2: > > * Removed an accidental double free I let slip in in > > sctp_association_free > > * Removed now unused cookie variable > > --- > > net/sctp/sm_make_chunk.c | 13 +++---------- > > net/sctp/sm_sideeffect.c | 5 +++++ > > 2 files changed, 8 insertions(+), 10 deletions(-) > > > > diff --git a/net/sctp/sm_make_chunk.c b/net/sctp/sm_make_chunk.c > > index 72e74503f9fc..8e12e19fe42d 100644 > > --- a/net/sctp/sm_make_chunk.c > > +++ b/net/sctp/sm_make_chunk.c > > @@ -2327,7 +2327,6 @@ int sctp_process_init(struct sctp_association *asoc, struct sctp_chunk *chunk, > > union sctp_addr addr; > > struct sctp_af *af; > > int src_match = 0; > > - char *cookie; > > > > /* We must include the address that the INIT packet came from. > > * This is the only address that matters for an INIT packet. > > @@ -2431,14 +2430,6 @@ int sctp_process_init(struct sctp_association *asoc, struct sctp_chunk *chunk, > > /* Peer Rwnd : Current calculated value of the peer's rwnd. */ > > asoc->peer.rwnd = asoc->peer.i.a_rwnd; > > > > - /* Copy cookie in case we need to resend COOKIE-ECHO. */ > > - cookie = asoc->peer.cookie; > > - if (cookie) { > > - asoc->peer.cookie = kmemdup(cookie, asoc->peer.cookie_len, gfp); > > - if (!asoc->peer.cookie) > > - goto clean_up; > > - } > > - > > /* RFC 2960 7.2.1 The initial value of ssthresh MAY be arbitrarily > > * high (for example, implementations MAY use the size of the receiver > > * advertised window). > > @@ -2607,7 +2598,9 @@ static int sctp_process_param(struct sctp_association *asoc, > > case SCTP_PARAM_STATE_COOKIE: > > asoc->peer.cookie_len = > > ntohs(param.p->length) - sizeof(struct sctp_paramhdr); > > - asoc->peer.cookie = param.cookie->body; > > + asoc->peer.cookie = kmemdup(param.cookie->body, asoc->peer.cookie_len, gfp); > > + if (!asoc->peer.cookie) > > + retval = 0; > > break; > > > > case SCTP_PARAM_HEARTBEAT_INFO: > > diff --git a/net/sctp/sm_sideeffect.c b/net/sctp/sm_sideeffect.c > > index 4aa03588f87b..27ddf2d8f001 100644 > > --- a/net/sctp/sm_sideeffect.c > > +++ b/net/sctp/sm_sideeffect.c > > @@ -898,6 +898,11 @@ static void sctp_cmd_new_state(struct sctp_cmd_seq *cmds, > > asoc->rto_initial; > > } > > > > + if (sctp_state(asoc, ESTABLISHED)) { > > + kfree(asoc->peer.cookie); > > + asoc->peer.cookie = NULL; > > + } > > + > > if (sctp_state(asoc, ESTABLISHED) || > > sctp_state(asoc, CLOSED) || > > sctp_state(asoc, SHUTDOWN_RECEIVED)) { > > -- > > 2.20.1 > > >