GNU bug report logs - #23040
"Stack overflow in regexp matcher" when entering group

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Nikolaus Rath <Nikolaus <at> rath.org>
To: submit <at> debbugs.gnu.org (The Gnus Bugfixing Girls + Boys)
Subject: "Stack overflow in regexp matcher" when entering group
Date: Thu, 17 Mar 2016 08:24:45 -0700

Hello,

When attempting to enter an nnimap group, I'm getting the following
error:

Debugger entered--Lisp error: (error "Stack overflow in regexp matcher")
  re-search-forward("<.+@[a-z0-9]+\\.rath\\.org>" nil t)
  gnus-score-string((((touched nil) ("references" ("<.+@[a-z0-9]+\\.rath\\.org>" nil nil r)))) "references" 736040 736012 nil)
  gnus-score-headers(("/home/nikratio/lib/gnus/Score/all.SCORE" "/home/nikratio/lib/gnus/Score/nnimap:Junk Mail.SCORE") nil)
  gnus-possibly-score-headers()
  (progn (gnus-possibly-score-headers))
  (if gnus-use-scoring (progn (gnus-possibly-score-headers)))
  (cond ((not new-group) (gnus-set-global-variables) (if kill-buffer (progn (gnus-kill-or-deaden-summary kill-buffer))) (gnus-configure-windows (quote summary) (quote force)) (gnus-set-mode-line (quote summary)) (gnus-summary-position-point) (message "") t) ((null did-select) (if (and (derived-mode-p (quote gnus-summary-mode)) (not (equal (current-buffer) kill-buffer))) (progn (kill-buffer (current-buffer)) (if (not quit-config) (progn (gnus-summary-update-info) (set-buffer gnus-group-buffer) (gnus-group-jump-to-group group) (gnus-group-next-unread-group 1)) (gnus-handle-ephemeral-exit quit-config)))) (if (null (gnus-list-of-unread-articles group)) (gnus-message 3 "Group %s contains no messages" group) (gnus-message 3 "Can't select group")) nil) ((eq did-select (quote quit)) (and (derived-mode-p (quote gnus-summary-mode)) (not (equal (current-buffer) kill-buffer)) (kill-buffer (current-buffer))) (if kill-buffer (progn (gnus-kill-or-deaden-summary kill-buffer))) (if (not quit-config) (progn (set-buffer gnus-group-buffer) (gnus-group-jump-to-group group) (gnus-configure-windows (quote group) (quote force))) (gnus-handle-ephemeral-exit quit-config)) (signal (quote quit) nil)) (t (gnus-set-global-variables) (if (boundp (quote spam-install-hooks)) (progn (spam-initialize))) (setq gnus-newsgroup-active (gnus-copy-sequence (symbol-value (intern-soft gnus-newsgroup-name gnus-active-hashtb)))) (setq gnus-newsgroup-highest (cdr gnus-newsgroup-active)) (gnus-run-hooks (quote gnus-select-group-hook)) (if (memq (quote summary) (gnus-update-format-specifications nil (quote summary) (quote summary-mode) (quote summary-dummy))) (progn (gnus-update-summary-mark-positions))) (if gnus-use-scoring (progn (gnus-possibly-score-headers))) (if gnus-build-sparse-threads (progn (gnus-build-sparse-threads))) (if show-all (let ((gnus-newsgroup-dormant nil)) (gnus-summary-initial-limit show-all)) (gnus-summary-initial-limit show-all)) (if no-display nil (gnus-summary-prepare)) (if gnus-use-trees (progn (gnus-tree-open) (setq gnus-summary-highlight-line-function (quote gnus-tree-highlight-article)))) (if (and (zerop (buffer-size)) (not no-display)) (progn (cond (gnus-newsgroup-dormant (gnus-summary-limit-include-dormant)) ((and gnus-newsgroup-scored show-all) (gnus-summary-limit-include-expunged t))))) (gnus-run-hooks (quote gnus-apply-kill-hook)) (if (and (zerop (buffer-size)) (not no-display)) (progn (gnus-summary-catchup-and-exit nil t) (gnus-message 6 "No unread news") (if kill-buffer (progn (gnus-kill-or-deaden-summary kill-buffer))) nil) (gnus-summary-maybe-hide-threads) (gnus-configure-windows (quote summary)) (if kill-buffer (progn (gnus-kill-or-deaden-summary kill-buffer))) (gnus-summary-auto-select-subject) (if (and (not no-article) (not no-display) gnus-newsgroup-unreads gnus-auto-select-first) (progn (let ((art ...)) (if (and art gnus-plugged ... ...) (progn ...)))) (gnus-summary-position-point) (gnus-configure-windows (quote summary) (quote force)) (gnus-set-mode-line (quote summary))) (if (and gnus-auto-center-group (get-buffer-window gnus-group-buffer t)) (progn (let ((owin ...)) (select-window (get-buffer-window gnus-group-buffer t)) (if (gnus-group-goto-group group) (progn ...)) (select-window owin)))) (setq gnus-newsgroup-prepared t) (gnus-run-hooks (quote gnus-summary-prepared-hook)) (if (gnus-ephemeral-group-p group) nil (gnus-group-update-group group nil t)) t)))
  (let* ((new-group (gnus-summary-setup-buffer group)) (quit-config (gnus-group-quit-config group)) (did-select (and new-group (gnus-select-newsgroup group show-all select-articles)))) (cond ((not new-group) (gnus-set-global-variables) (if kill-buffer (progn (gnus-kill-or-deaden-summary kill-buffer))) (gnus-configure-windows (quote summary) (quote force)) (gnus-set-mode-line (quote summary)) (gnus-summary-position-point) (message "") t) ((null did-select) (if (and (derived-mode-p (quote gnus-summary-mode)) (not (equal (current-buffer) kill-buffer))) (progn (kill-buffer (current-buffer)) (if (not quit-config) (progn (gnus-summary-update-info) (set-buffer gnus-group-buffer) (gnus-group-jump-to-group group) (gnus-group-next-unread-group 1)) (gnus-handle-ephemeral-exit quit-config)))) (if (null (gnus-list-of-unread-articles group)) (gnus-message 3 "Group %s contains no messages" group) (gnus-message 3 "Can't select group")) nil) ((eq did-select (quote quit)) (and (derived-mode-p (quote gnus-summary-mode)) (not (equal (current-buffer) kill-buffer)) (kill-buffer (current-buffer))) (if kill-buffer (progn (gnus-kill-or-deaden-summary kill-buffer))) (if (not quit-config) (progn (set-buffer gnus-group-buffer) (gnus-group-jump-to-group group) (gnus-configure-windows (quote group) (quote force))) (gnus-handle-ephemeral-exit quit-config)) (signal (quote quit) nil)) (t (gnus-set-global-variables) (if (boundp (quote spam-install-hooks)) (progn (spam-initialize))) (setq gnus-newsgroup-active (gnus-copy-sequence (symbol-value (intern-soft gnus-newsgroup-name gnus-active-hashtb)))) (setq gnus-newsgroup-highest (cdr gnus-newsgroup-active)) (gnus-run-hooks (quote gnus-select-group-hook)) (if (memq (quote summary) (gnus-update-format-specifications nil (quote summary) (quote summary-mode) (quote summary-dummy))) (progn (gnus-update-summary-mark-positions))) (if gnus-use-scoring (progn (gnus-possibly-score-headers))) (if gnus-build-sparse-threads (progn (gnus-build-sparse-threads))) (if show-all (let ((gnus-newsgroup-dormant nil)) (gnus-summary-initial-limit show-all)) (gnus-summary-initial-limit show-all)) (if no-display nil (gnus-summary-prepare)) (if gnus-use-trees (progn (gnus-tree-open) (setq gnus-summary-highlight-line-function (quote gnus-tree-highlight-article)))) (if (and (zerop (buffer-size)) (not no-display)) (progn (cond (gnus-newsgroup-dormant (gnus-summary-limit-include-dormant)) ((and gnus-newsgroup-scored show-all) (gnus-summary-limit-include-expunged t))))) (gnus-run-hooks (quote gnus-apply-kill-hook)) (if (and (zerop (buffer-size)) (not no-display)) (progn (gnus-summary-catchup-and-exit nil t) (gnus-message 6 "No unread news") (if kill-buffer (progn (gnus-kill-or-deaden-summary kill-buffer))) nil) (gnus-summary-maybe-hide-threads) (gnus-configure-windows (quote summary)) (if kill-buffer (progn (gnus-kill-or-deaden-summary kill-buffer))) (gnus-summary-auto-select-subject) (if (and (not no-article) (not no-display) gnus-newsgroup-unreads gnus-auto-select-first) (progn (let (...) (if ... ...))) (gnus-summary-position-point) (gnus-configure-windows (quote summary) (quote force)) (gnus-set-mode-line (quote summary))) (if (and gnus-auto-center-group (get-buffer-window gnus-group-buffer t)) (progn (let (...) (select-window ...) (if ... ...) (select-window owin)))) (setq gnus-newsgroup-prepared t) (gnus-run-hooks (quote gnus-summary-prepared-hook)) (if (gnus-ephemeral-group-p group) nil (gnus-group-update-group group nil t)) t))))
  gnus-summary-read-group-1("nnimap:Junk Mail" nil nil nil nil nil)
  (or (gnus-summary-read-group-1 group show-all no-article kill-buffer no-display select-articles) (setq show-all nil select-articles nil))
  (let ((gnus-auto-select-next nil)) (or (gnus-summary-read-group-1 group show-all no-article kill-buffer no-display select-articles) (setq show-all nil select-articles nil)))
  (setq result (let ((gnus-auto-select-next nil)) (or (gnus-summary-read-group-1 group show-all no-article kill-buffer no-display select-articles) (setq show-all nil select-articles nil))))
  (null (setq result (let ((gnus-auto-select-next nil)) (or (gnus-summary-read-group-1 group show-all no-article kill-buffer no-display select-articles) (setq show-all nil select-articles nil)))))
  (and group (null (setq result (let ((gnus-auto-select-next nil)) (or (gnus-summary-read-group-1 group show-all no-article kill-buffer no-display select-articles) (setq show-all nil select-articles nil))))) (eq gnus-auto-select-next (quote quietly)))
  (while (and group (null (setq result (let ((gnus-auto-select-next nil)) (or (gnus-summary-read-group-1 group show-all no-article kill-buffer no-display select-articles) (setq show-all nil select-articles nil))))) (eq gnus-auto-select-next (quote quietly))) (set-buffer gnus-group-buffer) (if backward (progn (gnus-group-prev-unread-group 2))) (if (not (equal group (gnus-group-group-name))) (setq group (gnus-group-group-name)) (setq group nil)))
  (let (result) (while (and group (null (setq result (let ((gnus-auto-select-next nil)) (or (gnus-summary-read-group-1 group show-all no-article kill-buffer no-display select-articles) (setq show-all nil select-articles nil))))) (eq gnus-auto-select-next (quote quietly))) (set-buffer gnus-group-buffer) (if backward (progn (gnus-group-prev-unread-group 2))) (if (not (equal group (gnus-group-group-name))) (setq group (gnus-group-group-name)) (setq group nil))) result)
  gnus-summary-read-group("nnimap:Junk Mail" nil nil nil nil nil nil)
  gnus-group-read-group(nil nil nil)
  gnus-topic-read-group(nil)
  call-interactively(gnus-topic-read-group nil nil)
  command-execute(gnus-topic-read-group)



Ma Gnus v0.14
GNU Emacs 24.4.1 (x86_64-pc-linux-gnu, GTK+ Version 3.14.5)
 of 2015-03-07 on trouble, modified by Debian


Best,
-Nikolaus

-- 
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Fingerprint: ED31 791B 2C5C 1613 AF38 8B8A D113 FCAC 3C4E 599F

             »Time flies like an arrow, fruit flies like a Banana.«

Message #8 received at 23040 <at> debbugs.gnu.org (full text, mbox):

From: Nikolaus Rath <Nikolaus <at> rath.org>
To: 23040 <at> debbugs.gnu.org 
Subject: Resolved
Date: Wed, 27 Apr 2016 08:34:28 -0700

The problem here is that recently some spam has started to come with
extremely long "References" headers, and that the regular expression
used in one of my scoring rules is sub-optimal when applied to such long
strings.

In particular, the leading dot in "<.+@[a-z0-9]+\\.rath\\.org>" first
matches the entire reference header, and then emacs presumably has to
backtrack character by character (or something like that).

Fixing the rule by restricting the match to one message id fixes the
problem: "<[^<>@]+@[a-z0-9]+\\.rath\\.org>"

Best,
-Nikolaus

-- 
GPG encrypted emails preferred. Key id: 0xD113FCAC3C4E599F
Fingerprint: ED31 791B 2C5C 1613 AF38 8B8A D113 FCAC 3C4E 599F

             »Time flies like an arrow, fruit flies like a Banana.«

Message #15 received at 23040 <at> debbugs.gnu.org (full text, mbox):

From: Lars Ingebrigtsen <larsi <at> gnus.org>
To: Nikolaus Rath <Nikolaus <at> rath.org>
Cc: 23040 <at> debbugs.gnu.org
Subject: Re: bug#23040: Resolved
Date: Thu, 26 Jan 2017 23:55:25 +0100

Nikolaus Rath <Nikolaus <at> rath.org> writes:

> The problem here is that recently some spam has started to come with
> extremely long "References" headers, and that the regular expression
> used in one of my scoring rules is sub-optimal when applied to such long
> strings.
>
> In particular, the leading dot in "<.+@[a-z0-9]+\\.rath\\.org>" first
> matches the entire reference header, and then emacs presumably has to
> backtrack character by character (or something like that).
>
> Fixing the rule by restricting the match to one message id fixes the
> problem: "<[^<>@]+@[a-z0-9]+\\.rath\\.org>"

Could you submit a patch for this problem? 

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

Message #18 received at 23040 <at> debbugs.gnu.org (full text, mbox):

From: Nikolaus Rath <Nikolaus <at> rath.org>
To: Lars Ingebrigtsen <larsi <at> gnus.org>
Cc: 23040 <at> debbugs.gnu.org
Subject: Re: bug#23040: Resolved
Date: Fri, 27 Jan 2017 09:56:39 -0800

On Jan 26 2017, Lars Ingebrigtsen <larsi <at> gnus.org> wrote:
> Nikolaus Rath <Nikolaus <at> rath.org> writes:
>
>> The problem here is that recently some spam has started to come with
>> extremely long "References" headers, and that the regular expression
>> used in one of my scoring rules is sub-optimal when applied to such long
>> strings.
>>
>> In particular, the leading dot in "<.+@[a-z0-9]+\\.rath\\.org>" first
>> matches the entire reference header, and then emacs presumably has to
>> backtrack character by character (or something like that).
>>
>> Fixing the rule by restricting the match to one message id fixes the
>> problem: "<[^<>@]+@[a-z0-9]+\\.rath\\.org>"
>
> Could you submit a patch for this problem? 

If I understand the issue correctly, then it is caused by a sub-optimal
regular expression in my local configuration that triggers problems in
Emacs' regular expression engine. I think the former can't be patched in
Gnus, and the latter is definitely beyond my area of expertise, sorry.


Best,
-Nikolaus

-- 
GPG encrypted emails preferred. Key id: 0xD113FCAC3C4E599F
Fingerprint: ED31 791B 2C5C 1613 AF38 8B8A D113 FCAC 3C4E 599F

             »Time flies like an arrow, fruit flies like a Banana.«

Message #21 received at 23040 <at> debbugs.gnu.org (full text, mbox):

From: Lars Ingebrigtsen <larsi <at> gnus.org>
To: Nikolaus Rath <Nikolaus <at> rath.org>
Cc: 23040 <at> debbugs.gnu.org
Subject: Re: bug#23040: Resolved
Date: Fri, 27 Jan 2017 20:09:13 +0100

Nikolaus Rath <Nikolaus <at> rath.org> writes:

> If I understand the issue correctly, then it is caused by a sub-optimal
> regular expression in my local configuration that triggers problems in
> Emacs' regular expression engine. I think the former can't be patched in
> Gnus, and the latter is definitely beyond my area of expertise, sorry.

OK; closing.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

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