linux-kernel - Re: [PATCH 4/4] file: Fix file descriptor leak in copy_fd

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Date:   Tue, 29 Mar 2022 15:23:10 -0700
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Fedor Pchelkin <aissur0002@...il.com>
Cc:     Alexey Khoroshilov <khoroshilov@...ras.ru>,
        Eric Biggers <ebiggers@...nel.org>,
        Christian Brauner <brauner@...nel.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/4] file: Fix file descriptor leak in copy_fd_bitmaps()

On Tue, Mar 29, 2022 at 3:18 PM Linus Torvalds
<torvalds@...ux-foundation.org> wrote:
>
> Ok, applied as commit 1c24a186398f ("fs: fd tables have to be
> multiples of BITS_PER_LONG").

Oh, forgot to mention...

Christian - it strikes me that the whole "min(count, max_fds)" in
sane_fdtable_size() is a bit stupid.

A _smarter_ approach might be to pass in 'max_fds' to
count_open_files(), and simply not count past that value.

I didn't do that, because I wanted to keep the patch obvious. And it
probably doesn't matter, but it's kind of silly to possibly count a
lot of open files that we want to close anyway, when we already know
the place we should stop counting.

Whatever. I just wanted to mention it in case you decide you want to
clean that part up. This is mostly your code anyway.

               Linus