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From: Leon Romanovsky <leon@kernel.org>
To: asmadeus@codewreck.org
Cc: syzbot <syzbot+67d13108d855f451cafc@syzkaller.appspotmail.com>,
	davem@davemloft.net, edumazet@google.com, ericvh@gmail.com,
	kuba@kernel.org, linux-kernel@vger.kernel.org,
	linux_oss@crudebyte.com, lucho@ionkov.net,
	netdev@vger.kernel.org, pabeni@redhat.com,
	syzkaller-bugs@googlegroups.com,
	v9fs-developer@lists.sourceforge.net
Subject: Re: [syzbot] KASAN: use-after-free Read in rdma_close
Date: Wed, 28 Sep 2022 14:54:03 +0300	[thread overview]
Message-ID: <YzQ12+jtARpwS5bw@unreal> (raw)
In-Reply-To: <YzQuoqyGsooyDfId@codewreck.org>

On Wed, Sep 28, 2022 at 08:23:14PM +0900, asmadeus@codewreck.org wrote:
> Leon Romanovsky wrote on Wed, Sep 28, 2022 at 01:49:19PM +0300:
> > > But I agree I did get that wrong: trans_mod->close() wasn't called if
> > > create failed.
> > > We do want the idr_for_each_entry() that is in p9_client_destroy so
> > > rather than revert the commit (fix a bug, create a new one..) I'd rather
> > > split it out in an internal function that takes a 'bool close' or
> > > something to not duplicate the rest.
> > > (Bit of a nitpick, sure)
> > 
> > Please do proper unwind without extra variable.
> > 
> > Proper unwind means that you will call to symmetrical functions in
> > destroy as you used in create:
> > alloc -> free
> > create -> close
> > e.t.c
> > 
> > When you use some global function like you did, there is huge chance
> > to see unwind bugs.
> 
> No.

Let's agree to disagree.

> 
> Duplicating complicated cleanup code leads to leaks like we used to
> have; that destroy function already frees up things in the right order.

It is pretty straightforward code, nothing complex there.

Just pause for a minute, and ask yourself how totally random guy who
looked on this syzbot bug just because RDMA name in it, found the issue
so quickly.

I will give a hint, I saw not symmetrical error unwind in call trace.

Thanks

  reply	other threads:[~2022-09-28 11:54 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-09-25 11:29 [syzbot] KASAN: use-after-free Read in rdma_close syzbot
2022-09-28 10:07 ` Leon Romanovsky
2022-09-28 10:43   ` asmadeus
2022-09-28 10:49     ` Leon Romanovsky
2022-09-28 11:23       ` asmadeus
2022-09-28 11:54         ` Leon Romanovsky [this message]
2022-09-28 12:57           ` Christian Schoenebeck
2022-09-28 21:52             ` asmadeus
2022-09-29  6:10               ` Leon Romanovsky
2022-09-28 21:44   ` [PATCH 1/2] 9p: client_create/destroy: only call trans_mod->close after create Dominique Martinet
2022-09-28 21:44     ` [PATCH 2/2] 9p: client_create: init fcall_cache earlier Dominique Martinet
2022-09-29  5:57       ` Leon Romanovsky
2022-09-29  7:03         ` Dominique Martinet
2022-09-28 21:58     ` [PATCH 1/2 v2] 9p: client_create/destroy: only call trans_mod->close after create Dominique Martinet
2022-09-28 22:19       ` [PATCH v3] " Dominique Martinet
2022-09-29  5:54         ` Leon Romanovsky
2022-09-29  7:24           ` Dominique Martinet
2022-12-30 10:34 ` [syzbot] KASAN: use-after-free Read in rdma_close syzbot
2023-01-13 10:35 ` syzbot
2023-01-27 10:36 ` syzbot
2023-02-10 10:36 ` syzbot
2023-02-24 10:37 ` syzbot
2023-03-10 10:38 ` syzbot
2023-03-24 10:38 ` syzbot
2023-04-07 10:38 ` syzbot
2023-04-21 10:39 ` syzbot
2023-05-05 10:40 ` syzbot
2023-05-19 10:40 ` syzbot
2023-06-02 10:42 ` syzbot
2023-06-02 10:57   ` Aleksandr Nogikh

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