From: Alexey Dobriyan <adobriyan@gmail.com>
To: Eric Biggers <ebiggers@kernel.org>
Cc: Jia-Ju Bai <baijiaju1990@gmail.com>,
christian@brauner.io, ebiederm@xmission.com,
akpm@linux-foundation.org, keescook@chromium.org,
gladkov.alexey@gmail.com, walken@google.com,
bernd.edlinger@hotmail.de, avagin@gmail.com, deller@gmx.de,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH] fs: proc: fix error return code of proc_map_files_readdir()
Date: Tue, 9 Mar 2021 22:05:11 +0300 [thread overview]
Message-ID: <YEfG54xMM7OtPEE5@localhost.localdomain> (raw)
In-Reply-To: <YEe+v+ywMrxgmj05@gmail.com>
On Tue, Mar 09, 2021 at 10:30:23AM -0800, Eric Biggers wrote:
> On Tue, Mar 09, 2021 at 01:55:27AM -0800, Jia-Ju Bai wrote:
> > When get_task_mm() returns NULL to mm, no error return code of
> > proc_map_files_readdir() is assigned.
> > To fix this bug, ret is assigned with -ENOENT in this case.
> > --- a/fs/proc/base.c
> > +++ b/fs/proc/base.c
> > @@ -2332,8 +2332,10 @@ proc_map_files_readdir(struct file *file, struct dir_context *ctx)
> > goto out_put_task;
> >
> > mm = get_task_mm(task);
> > - if (!mm)
> > + if (!mm) {
> > + ret = -ENOENT;
> > goto out_put_task;
> > + }
> >
> > ret = mmap_read_lock_killable(mm);
>
> Is there something in particular that makes you think that returning ENOENT is
> the correct behavior in this case? Try 'ls /proc/$pid/map_files' where pid is a
> kernel thread; it's an empty directory, which is probably intentional. Your
> patch would change reading the directory to fail with ENOENT.
Yes. 0 from readdir means "no more stuff", not an error.
next prev parent reply other threads:[~2021-03-09 19:05 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-09 9:55 [PATCH] fs: proc: fix error return code of proc_map_files_readdir() Jia-Ju Bai
2021-03-09 18:30 ` Eric Biggers
2021-03-09 19:05 ` Alexey Dobriyan [this message]
2021-03-10 1:11 ` Jia-Ju Bai
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