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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id DA4D5C433FE for ; Wed, 23 Nov 2022 18:14:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239674AbiKWSOv (ORCPT ); Wed, 23 Nov 2022 13:14:51 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40632 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238849AbiKWSNy (ORCPT ); Wed, 23 Nov 2022 13:13:54 -0500 Received: from mail-ot1-x32f.google.com (mail-ot1-x32f.google.com [IPv6:2607:f8b0:4864:20::32f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E828A11A0F; Wed, 23 Nov 2022 10:10:48 -0800 (PST) Received: by mail-ot1-x32f.google.com with SMTP id a13-20020a9d6e8d000000b00668d65fc44fso11706585otr.9; Wed, 23 Nov 2022 10:10:48 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=j6r0CC9TisfV7wm8BdBdWohmuoxOFNGRQTl2jwbJACo=; b=CgPoGiIG3pBrp7eujX56xc48VPf1EZn44oEbSpWQyQSdv6uFHhdJWy4d+cfIsMU9dU +y3T0Pg6+qapLPHu9jFJ9nROcc3eZrxISUrnnPwjkUYWQxJFwbmmghk3FwLikwLzRnKL pQYu4e7kBKSTt4JTTfd9iErXaDWaUCP6iiosBRzimlXDgsWO0pfTvOuM4rI7MFEv8w86 nJQdeL7tfcOiPTJxMCTlMrJgpg0/f4T2OY+LO7rPuu4fiptcf/7VmR/OFUT8yS55XZ2l PJpDI0PwXC5+2u4eNtY62MG+cfRG+hP1RJKwacLydlFgrRfwyRiEb8rjZe0q7y6c7pQE CS+w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=j6r0CC9TisfV7wm8BdBdWohmuoxOFNGRQTl2jwbJACo=; b=nZ8G4FmeYFPH4XxI9VL1g5w0ugEoQqgwDBWpn5gycyRT3zB6IaAk7/CCtHT9r1h3/x TnndBhbrw5LMHtGFjSox2ORF+znD/F0AcZ/xNuqObwzx/XL7s1Dujfg4wv3Ujy2Yzmet sPTYn5aQzHYe8no8d9R0H8kB4YdradyGlAb34ZvgWFOzZdYfny5XDTapaQFsbwdEPK3h mJ//Ney/1OoUrVnwOlos4pgXrDrOShLUr0ShNU5isCfIEQJqf3eT4t1UyWm5vwV8G8TG jcK4NZOSW8qpAwiWZ6sfKdlo/uUinnYcZrEl/Cy3YdEZxqVsN5w0SwrimQdHEOddhYHI Uvyg== X-Gm-Message-State: ANoB5pmDJaB2B2rysBJpp3AragMPCTm5dZN4kyDXxLPJnuVC+H+b59ek PPnifwTe51nFKgUdZ3FUjzQ= X-Google-Smtp-Source: AA0mqf6/xIwU3vxvBKYK1+Ir4kN0laorPiDEZZHCpbZxLCoUhRYxgSVWtrEKrNn/KFz2Jdkbdg5cog== X-Received: by 2002:a05:6830:13c9:b0:66c:a3a8:3870 with SMTP id e9-20020a05683013c900b0066ca3a83870mr5537218otq.54.1669227048082; Wed, 23 Nov 2022 10:10:48 -0800 (PST) Received: from t14s.localdomain ([2001:1284:f016:5412:fa8e:2d33:bd7c:54c7]) by smtp.gmail.com with ESMTPSA id q8-20020aca4308000000b0035b7002af8csm1665966oia.56.2022.11.23.10.10.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 23 Nov 2022 10:10:47 -0800 (PST) Received: by t14s.localdomain (Postfix, from userid 1000) id 633ED459D27; Wed, 23 Nov 2022 15:10:45 -0300 (-03) Date: Wed, 23 Nov 2022 15:10:45 -0300 From: Marcelo Ricardo Leitner To: Xin Long Cc: Zhengchao Shao , linux-sctp@vger.kernel.org, netdev@vger.kernel.org, vyasevich@gmail.com, nhorman@tuxdriver.com, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, weiyongjun1@huawei.com, yuehaibing@huawei.com, Tetsuo Handa Subject: Re: [PATCH net] sctp: fix memory leak in sctp_stream_outq_migrate() Message-ID: References: <20221118085030.121297-1-shaozhengchao@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Wed, Nov 23, 2022 at 12:20:44PM -0500, Xin Long wrote: > On Tue, Nov 22, 2022 at 6:35 PM Marcelo Ricardo Leitner > wrote: > > > > On Fri, Nov 18, 2022 at 10:15:50PM -0500, Xin Long wrote: > > > On Fri, Nov 18, 2022 at 3:48 AM Zhengchao Shao wrote: > > > > > > > > When sctp_stream_outq_migrate() is called to release stream out resources, > > > > the memory pointed to by prio_head in stream out is not released. > > > > > > > > The memory leak information is as follows: > > > > unreferenced object 0xffff88801fe79f80 (size 64): > > > > comm "sctp_repo", pid 7957, jiffies 4294951704 (age 36.480s) > > > > hex dump (first 32 bytes): > > > > 80 9f e7 1f 80 88 ff ff 80 9f e7 1f 80 88 ff ff ................ > > > > 90 9f e7 1f 80 88 ff ff 90 9f e7 1f 80 88 ff ff ................ > > > > backtrace: > > > > [] kmalloc_trace+0x26/0x60 > > > > [] sctp_sched_prio_set+0x4cc/0x770 > > > > [] sctp_stream_init_ext+0xd2/0x1b0 > > > > [] sctp_sendmsg_to_asoc+0x1614/0x1a30 > > > > [] sctp_sendmsg+0xda1/0x1ef0 > > > > [] inet_sendmsg+0x9d/0xe0 > > > > [] sock_sendmsg+0xd3/0x120 > > > > [] __sys_sendto+0x23a/0x340 > > > > [] __x64_sys_sendto+0xe1/0x1b0 > > > > [] do_syscall_64+0x39/0xb0 > > > > [] entry_SYSCALL_64_after_hwframe+0x63/0xcd > > > > > > > > Fixes: 637784ade221 ("sctp: introduce priority based stream scheduler") > > > > Reported-by: syzbot+29c402e56c4760763cc0@syzkaller.appspotmail.com > > > > Signed-off-by: Zhengchao Shao > > > > --- > > > > net/sctp/stream.c | 6 ++++++ > > > > 1 file changed, 6 insertions(+) > > > > > > > > diff --git a/net/sctp/stream.c b/net/sctp/stream.c > > > > index ef9fceadef8d..a17dc368876f 100644 > > > > --- a/net/sctp/stream.c > > > > +++ b/net/sctp/stream.c > > > > @@ -70,6 +70,9 @@ static void sctp_stream_outq_migrate(struct sctp_stream *stream, > > > > * sctp_stream_update will swap ->out pointers. > > > > */ > > > > for (i = 0; i < outcnt; i++) { > > > > + if (SCTP_SO(new, i)->ext) > > > > + kfree(SCTP_SO(new, i)->ext->prio_head); > > > > + > > > > kfree(SCTP_SO(new, i)->ext); > > > > SCTP_SO(new, i)->ext = SCTP_SO(stream, i)->ext; > > > > SCTP_SO(stream, i)->ext = NULL; > > > > @@ -77,6 +80,9 @@ static void sctp_stream_outq_migrate(struct sctp_stream *stream, > > > > } > > > > > > > > for (i = outcnt; i < stream->outcnt; i++) { > > > > + if (SCTP_SO(stream, i)->ext) > > > > + kfree(SCTP_SO(stream, i)->ext->prio_head); > > > > + > > > > kfree(SCTP_SO(stream, i)->ext); > > > > SCTP_SO(stream, i)->ext = NULL; > > > > } > > > > -- > > > > 2.17.1 > > > > > > > This is not a proper fix: > > > 1. you shouldn't access "prio_head" outside stream_sched_prio.c. > > > 2. the prio_head you freed might be used by other out streams, freeing > > > it unconditionally would cause either a double free or use after free. > > > > > > I'm afraid we have to add a ".free_sid" in sctp_sched_ops, and > > > implement it for sctp_sched_prio, like: > > > > > > +static void sctp_sched_prio_free_sid(struct sctp_stream *stream, __u16 sid) > > > +{ > > > + struct sctp_stream_priorities *prio = SCTP_SO(stream, > > > sid)->ext->prio_head; > > > + int i; > > > + > > > + if (!prio) > > > + return; > > > + > > > + SCTP_SO(stream, sid)->ext->prio_head = NULL; > > > + for (i = 0; i < stream->outcnt; i++) { > > > > Instead of checking all streams, the for() can/should be replaced by > > (from sctp_sched_prio_free): > > if (!list_empty(&prio->prio_sched)) > > return; > sctp_stream_outq_migrate() is called after unsched_all() for "stream", > list_empty(prio_sched) is expected to be true. Good point. Am I missing something or the 'prio_head == prio' below would always be false then as well? Anyhow, as this is moving to something that can potentially be called from other places afterwards, keeping the check doesn't hurt. > > Note that kfree(SCTP_SO(new, i)->ext) shouldn't have the reported > problem, as at that moment, the "new" stream hasn't been set > stream_sched yet. It means there's only one place that needs to > call free_sid in sctp_stream_outq_migrate(). > (Maybe Zhengchao can help us confirm this?) That's the case in Tetsuo's patch (earlier today) as well. Yet, if we have an official way to free a stream, if it's not error handling during initialization, it should use it. > > > > > > + if (SCTP_SO(stream, i)->ext && > > > + SCTP_SO(stream, i)->ext->prio_head == prio) > > > + return; > > > + } > > > + kfree(prio); > > > +} > > > + > > > static void sctp_sched_prio_free(struct sctp_stream *stream) > > > { > > > struct sctp_stream_priorities *prio, *n; > > > @@ -323,6 +340,7 @@ static struct sctp_sched_ops sctp_sched_prio = { > > > .get = sctp_sched_prio_get, > > > .init = sctp_sched_prio_init, > > > .init_sid = sctp_sched_prio_init_sid, > > > + .free_sid = sctp_sched_prio_free_sid, > > > .free = sctp_sched_prio_free, > > > .enqueue = sctp_sched_prio_enqueue, > > > .dequeue = sctp_sched_prio_dequeue, > > > > > > then call it in sctp_stream_outq_migrate(), like: > > > > > > +static void sctp_stream_free_ext(struct sctp_stream *stream, __u16 sid) > > > +{ > > > + struct sctp_sched_ops *sched = sctp_sched_ops_from_stream(stream); > > > + > > > + sched->free_sid(stream, sid); > > > + kfree(SCTP_SO(stream, sid)->ext); > > > + SCTP_SO(stream, sid)->ext = NULL; > > > +} > > > + > > > /* Migrates chunks from stream queues to new stream queues if needed, > > > * but not across associations. Also, removes those chunks to streams > > > * higher than the new max. > > > @@ -70,16 +79,14 @@ static void sctp_stream_outq_migrate(struct > > > sctp_stream *stream, > > > * sctp_stream_update will swap ->out pointers. > > > */ > > > for (i = 0; i < outcnt; i++) { > > > - kfree(SCTP_SO(new, i)->ext); > > > + sctp_stream_free_ext(new, i); > > > SCTP_SO(new, i)->ext = SCTP_SO(stream, i)->ext; > > > SCTP_SO(stream, i)->ext = NULL; > > > } > > > } > > > > > > - for (i = outcnt; i < stream->outcnt; i++) { > > > - kfree(SCTP_SO(stream, i)->ext); > > > - SCTP_SO(stream, i)->ext = NULL; > > > - } > > > + for (i = outcnt; i < stream->outcnt; i++) > > > + sctp_stream_free_ext(new, i); > > > } > > > > > > Marcelo, do you see a better solution? > > > > No. Your suggestion is the best I could think of too. > > > > Another approach would be to expose sched->free and do all the freeing > > at once, like sctp_stream_free() does. But the above is looks cleaner > > and makes it evident that freeing 'ext' is not trivial. > > > > With the proposal above, sctp_sched_prio_free() becomes an > > optimization, if we can call it that. With the for/if replacement > > above, not even that, and should be removed. Including sctp_sched_ops > > 'free' pointer. > Or we extract the common code to another function, like > sctp_sched_prio_free_head(stream, prio), and pass prio as > NULL in sctp_sched_prio_free() for freeing all. > > > > > sctp_stream_free() then should be updated to use the new > > sctp_stream_free_ext() instead, instead of mangling it directly. > I thought about this, but there is ".free", which is more efficient > to free all prio than calling ".free_sid" outcnt times. How much more efficient, just by avoiding retpoline stuff on the indirect functional call or something else? > > I may move free_sid() out of sctp_stream_free_ext(), then in > sctp_stream_free() we can call sctp_stream_free_ext() without > calling free_sid(), or just remove sctp_stream_free_ext(). It's easier to maintain it if we have symmetric paths for initializing and for freeing it and less special cases. We already have sctp_stream_init_ext(), so having sctp_stream_free_ext() is not off. I'm happy to review any patch that also updates sctp_stream_free(), one way or another. > > Thanks. > > > > > Makes sense? > > > > Thanks, > > Marcelo