[PATCH] emacs: fix MML quoting in replies

[Austin Clements]

On Sun,  4 Mar 2012 10:25:38 +0200, Jani Nikula <jani at nikula.org> wrote:
> The reply MML quoting added in commit ae438cc unintentionally MML
> quotes also the signature/encryption MML tags added via
> message-setup-hook, causing the reply not to be signed/encrypted.
> 
> MML quote just the original message in the temp buffer before
> inserting it to the message buffer, to not interfere with message mode
> hooks or message construction in general.
> 
> See [1] and [2] for bug reports.
> 
> Thanks to Tim Bielawa <tbielawa at redhat.com> for testing.
> 
> [1] id:"87hay78x6l.fsf at wyzanski.jamesvasile.com"
> [2] id:"1330812262-28272-1-git-send-email-tbielawa at redhat.com".
> 
> Signed-off-by: Jani Nikula <jani at nikula.org>
> ---
>  emacs/notmuch-mua.el |   10 ++++------
>  1 files changed, 4 insertions(+), 6 deletions(-)
> 
> diff --git a/emacs/notmuch-mua.el b/emacs/notmuch-mua.el
> index 4be7c13..13244eb 100644
> --- a/emacs/notmuch-mua.el
> +++ b/emacs/notmuch-mua.el
> @@ -95,6 +95,9 @@ list."
>  	      (goto-char (point-min))
>  	      (setq headers (mail-header-extract)))))
>        (forward-line 1)
> +      ;; Original message may contain (malicious) MML tags. We must
> +      ;; properly quote them in the reply.
> +      (mml-quote-region (point) (point-max))

Under what circumstances can the (re-search-forward "^$" nil t) above
this code fail?  If it does fail, is it possible for the (forward-line 1)
to move past an adversary-controlled line of text and fail to quote that
line?