linux-kernel - Re: [RFC][PATCH] Cross Memory Attach

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <AANLkTimNsDxeyZL4GVaH4L7YGO-EoRyCMHDtMPWU37hN@mail.gmail.com>
Date:	Wed, 15 Sep 2010 08:11:16 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Christopher Yeoh <cyeoh@....ibm.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [RFC][PATCH] Cross Memory Attach

On Tue, Sep 14, 2010 at 6:18 PM, Christopher Yeoh <cyeoh@....ibm.com> wrote:
> +
> +               if (copy_to) {
> +                       ret = copy_from_user(target_kaddr,
> +                                            user_buf + *bytes_copied,
> +                                            bytes_to_copy);
> +                       if (ret) {
> +                               kunmap(process_pages[i]);
> +                               goto end;
> +                       }
> +               } else {
> +                       ret = copy_to_user(user_buf + *bytes_copied,
> +                                          target_kaddr, bytes_to_copy);
> +                       if (ret) {
> +                               kunmap(process_pages[i]);
> +                               goto end;
> +                       }
> +               }
> +               kunmap(process_pages[i]);

Btw, please just do this as

   if (copy_to)
      ret = copy_from_user(..);
   else
      ret = copy_to_user(..);
   kunmap(process_pages[i]);
   if (ret)
      goto out;

(and also, I think you should probably use a real variable for
*bytes_copied, rather than update things behind the pointer. Update
the pointer just once at the end instead, or preferably just change
the calling convention to just return the number of bytes copied, and
let the caller do the page counting).

                      Linus
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/