linux-kernel - Re: [PATCH v2 2/2] fs: avoid fdput() after failed fdget() in kernel_read_file_from

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Message-ID: <20200522224702.GF11244@42.do-not-panic.com>
Date:   Fri, 22 May 2020 22:47:02 +0000
From:   Luis Chamberlain <mcgrof@...nel.org>
To:     Scott Branden <scott.branden@...adcom.com>
Cc:     Al Viro <viro@...iv.linux.org.uk>,
        Kees Cook <keescook@...omium.org>,
        Mimi Zohar <zohar@...ux.vnet.ibm.com>,
        linux-security-module <linux-security-module@...r.kernel.org>,
        James Morris <jmorris@...ei.org>,
        "Serge E. Hallyn" <serge@...lyn.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        Andrii Nakryiko <andriin@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...omium.org>,
        Shuah Khan <skhan@...uxfoundation.org>,
        Jens Axboe <axboe@...nel.dk>,
        Linux FS Devel <linux-fsdevel@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/2] fs: avoid fdput() after failed fdget() in
 kernel_read_file_from_fd()

On Fri, May 22, 2020 at 03:14:59PM -0700, Scott Branden wrote:
> 
> 
> On 2020-05-22 2:59 p.m., Scott Branden wrote:
> > Hi Luis,
> > 
> > On 2020-05-13 7:19 a.m., Luis Chamberlain wrote:
> > > On Wed, May 13, 2020 at 7:13 AM Luis Chamberlain <mcgrof@...nel.org>
> > > wrote:
> > > > On Wed, May 13, 2020 at 06:49:50AM +0100, Al Viro wrote:
> > > > > On Tue, May 12, 2020 at 01:43:05PM -0600, Shuah Khan wrote:
> > > > > > diff --git a/fs/exec.c b/fs/exec.c
> > > > > > index 06b4c550af5d..ea24bdce939d 100644
> > > > > > --- a/fs/exec.c
> > > > > > +++ b/fs/exec.c
> > > > > > @@ -1021,8 +1021,8 @@ int kernel_read_file_from_fd(int
> > > > > > fd, void **buf, loff_t *size, loff_t max_size,
> > > > > >              goto out;
> > > > > > 
> > > > > >      ret = kernel_read_file(f.file, buf, size, max_size, id);
> > > > > > -out:
> > > > > >      fdput(f);
> > > > > > +out:
> > > > > >      return ret;
> > > > > Incidentally, why is that thing exported?
> > > > Both kernel_read_file_from_fd() and kernel_read_file() are exported
> > > > because they have users, however kernel_read_file() only has security
> > > > stuff as a user. Do we want to get rid of the lsm hook for it?
> > > Alright, yeah just the export needs to be removed. I have a patch
> > > series dealing with these callers so will add it to my queue.
> > When will these changes make it into linux-next?
> > It is difficult for me to complete my patch series without these other
> > misc. changes in place.
> Sorry, I see the patch series is still being worked on (missing changelog,
> comments, etc).
> Hopefully the patches stabilize so I can apply my changes on top fairly
> soon.

Yeah I have to redo that series to take into account feedback. I'll be
sure cc you on that. I have a few other series to attend to before that,
so I think this will take a week.

  Luis