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Date: Tue, 19 Dec 2023 14:06:07 -0800
From: John Fastabend <john.fastabend@gmail.com>
To: John Fastabend <john.fastabend@gmail.com>, 
 John Fastabend <john.fastabend@gmail.com>, 
 Kuniyuki Iwashima <kuniyu@amazon.com>, 
 xrivendell7@gmail.com
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 kuniyu@amazon.com, 
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Message-ID: <658213cf198a3_96d8820886@john.notmuch>
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Subject: Re: memory leak in unix_create1/copy_process/security_prepare_creds
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John Fastabend wrote:
> John Fastabend wrote:
> > Kuniyuki Iwashima wrote:
> > > From: xingwei lee <xrivendell7@gmail.com>
> > > Date: Tue, 19 Dec 2023 17:12:25 +0800
> > > > Hello I found a bug in net/af_unix in the lastest upstream linux
> > > > 6.7.rc5 and comfired in lastest net/net-next/bpf/bpf-next tree.
> > > > Titled "TITLE: memory leak in unix_create1=E2=80=9D and I also up=
load the
> > > > repro.c and repro.txt.
> > > > =

> > > > If you fix this issue, please add the following tag to the commit=
:
> > > > Reported-by: xingwei Lee <xrivendell7@gmail.com>
> > > =

> > > Thanks for reporting!
> > > =

> > > It seems 8866730aed510 forgot to add sock_put().
> > > I've confirmed that the diff below silenced kmemleak but will check=

> > > more before posting a patch.
> > =

> > Did it really silence the memleak?
> =

> Yes reverting the patch fixed the issue for me.

The problem is we call proto update twice that bumps the refcnt
when adding a the same element to the map in the same slot. I'll fix
this on sockmap side so we can keep the current af_unix logic. Should
be able to push a fix tomorrow.

We probably never noticed for other socket types because its an
unusal replace to do same sock/same slot, but af_unix has this
side effect of incrementing the refcnt that doesn't exist elsewhere.

Thanks,
John=