* bug#9495: 24.0.50; Segfault in try_cursor_movement
@ 2011-09-13 19:28 Johan Bockgård
2011-09-14 5:22 ` Eli Zaretskii
0 siblings, 1 reply; 6+ messages in thread
From: Johan Bockgård @ 2011-09-13 19:28 UTC (permalink / raw)
To: 9495
Program terminated with signal 11, Segmentation fault.
#0 0x00007f5bccbe6fe7 in kill () at ../sysdeps/unix/syscall-template.S:82
82 ../sysdeps/unix/syscall-template.S: No such file or directory.
in ../sysdeps/unix/syscall-template.S
(gdb) bt
#0 0x00007f5bccbe6fe7 in kill () at ../sysdeps/unix/syscall-template.S:82
#1 0x000000000056e889 in fatal_error_signal (sig=11) at emacs.c:358
#2 <signal handler called>
#3 0x0000000000465f3f in try_cursor_movement (window=20987605, startp=...,
scroll_step=0x7fff5e400758) at xdisp.c:14639
xdisp.c:14639: (BUFFERP (g->object) && g->charpos == PT)
g is not a valid glyph here.
(gdb) p MATRIX_ROW (w->current_matrix, w->cursor.vpos).used[TEXT_AREA]
$3 = 80
(gdb) p w->cursor.hpos
$4 = 80
2011-09-13 Johan Bockgård <bojohan@gnu.org>
* xdisp.c (try_cursor_movement): Check bounds of hpos.
=== modified file 'src/xdisp.c'
--- src/xdisp.c 2011-09-09 01:06:52 +0000
+++ src/xdisp.c 2011-09-11 15:03:56 +0000
@@ -14627,7 +14627,11 @@ try_cursor_movement (Lisp_Object window,
is set, we are done. */
at_zv_p =
MATRIX_ROW (w->current_matrix, w->cursor.vpos)->ends_at_zv_p;
- if (!at_zv_p)
+ if (!at_zv_p
+ && w->cursor.hpos >= 0
+ && (w->cursor.hpos
+ < MATRIX_ROW_USED (w->current_matrix,
+ w->cursor.vpos)))
{
struct glyph_row *candidate =
MATRIX_ROW (w->current_matrix, w->cursor.vpos);
BTW, is this code in try_window_reusing_current_matrix correct?
struct glyph *glyph = row->glyphs[TEXT_AREA] + w->cursor.hpos;
struct glyph *end = glyph + row->used[TEXT_AREA];
It doesn't seem right for end to depend on hpos.
^ permalink raw reply [flat|nested] 6+ messages in thread
* bug#9495: 24.0.50; Segfault in try_cursor_movement
2011-09-13 19:28 bug#9495: 24.0.50; Segfault in try_cursor_movement Johan Bockgård
@ 2011-09-14 5:22 ` Eli Zaretskii
2011-09-14 19:50 ` Johan Bockgård
0 siblings, 1 reply; 6+ messages in thread
From: Eli Zaretskii @ 2011-09-14 5:22 UTC (permalink / raw)
To: Johan Bockgård; +Cc: 9495
> From: Johan Bockgård <bojohan@gnu.org>
> Date: Tue, 13 Sep 2011 21:28:17 +0200
>
>
> Program terminated with signal 11, Segmentation fault.
> #0 0x00007f5bccbe6fe7 in kill () at ../sysdeps/unix/syscall-template.S:82
> 82 ../sysdeps/unix/syscall-template.S: No such file or directory.
> in ../sysdeps/unix/syscall-template.S
> (gdb) bt
> #0 0x00007f5bccbe6fe7 in kill () at ../sysdeps/unix/syscall-template.S:82
> #1 0x000000000056e889 in fatal_error_signal (sig=11) at emacs.c:358
> #2 <signal handler called>
> #3 0x0000000000465f3f in try_cursor_movement (window=20987605, startp=...,
> scroll_step=0x7fff5e400758) at xdisp.c:14639
>
> xdisp.c:14639: (BUFFERP (g->object) && g->charpos == PT)
>
> g is not a valid glyph here.
>
> (gdb) p MATRIX_ROW (w->current_matrix, w->cursor.vpos).used[TEXT_AREA]
> $3 = 80
> (gdb) p w->cursor.hpos
> $4 = 80
Thanks. But what is the value of `rv' at that point?
> 2011-09-13 Johan Bockgård <bojohan@gnu.org>
>
> * xdisp.c (try_cursor_movement): Check bounds of hpos.
That will prevent your particular crash, but I'm not sure it's correct
in all cases (like R2L lines and other atrocities). Can you give a
recipe for reproducing this crash from "emacs -Q"? I'd like to
investigate a bit more. TIA.
> BTW, is this code in try_window_reusing_current_matrix correct?
>
> struct glyph *glyph = row->glyphs[TEXT_AREA] + w->cursor.hpos;
> struct glyph *end = glyph + row->used[TEXT_AREA];
No, it's a bug. I fixed it. Thanks for spotting it.
^ permalink raw reply [flat|nested] 6+ messages in thread
* bug#9495: 24.0.50; Segfault in try_cursor_movement
2011-09-14 5:22 ` Eli Zaretskii
@ 2011-09-14 19:50 ` Johan Bockgård
2011-09-15 3:12 ` Leo
2011-09-15 16:05 ` Eli Zaretskii
0 siblings, 2 replies; 6+ messages in thread
From: Johan Bockgård @ 2011-09-14 19:50 UTC (permalink / raw)
To: Eli Zaretskii; +Cc: 9495
Eli Zaretskii <eliz@gnu.org> writes:
>> From: Johan Bockgård <bojohan@gnu.org>
>> Date: Tue, 13 Sep 2011 21:28:17 +0200
>>
>>
>> Program terminated with signal 11, Segmentation fault.
>> #0 0x00007f5bccbe6fe7 in kill () at ../sysdeps/unix/syscall-template.S:82
>> 82 ../sysdeps/unix/syscall-template.S: No such file or directory.
>> in ../sysdeps/unix/syscall-template.S
>> (gdb) bt
>> #0 0x00007f5bccbe6fe7 in kill () at ../sysdeps/unix/syscall-template.S:82
>> #1 0x000000000056e889 in fatal_error_signal (sig=11) at emacs.c:358
>> #2 <signal handler called>
>> #3 0x0000000000465f3f in try_cursor_movement (window=20987605, startp=...,
>> scroll_step=0x7fff5e400758) at xdisp.c:14639
>>
>> xdisp.c:14639: (BUFFERP (g->object) && g->charpos == PT)
>>
>> g is not a valid glyph here.
>>
>> (gdb) p MATRIX_ROW (w->current_matrix, w->cursor.vpos).used[TEXT_AREA]
>> $3 = 80
>> (gdb) p w->cursor.hpos
>> $4 = 80
>
> Thanks. But what is the value of `rv' at that point?
1
>> 2011-09-13 Johan Bockgård <bojohan@gnu.org>
>>
>> * xdisp.c (try_cursor_movement): Check bounds of hpos.
>
> That will prevent your particular crash, but I'm not sure it's correct
> in all cases (like R2L lines and other atrocities). Can you give a
> recipe for reproducing this crash from "emacs -Q"? I'd like to
> investigate a bit more. TIA.
emacs -Q -eval '(setq line-move-visual nil truncate-lines t track-eol t)'
C-u 100 x RET
y <up>
At this point, in try_cursor_movement, point is in the "x" line, the
window has not yet hscrolled, and the value of hpos is just after the
last valid element in glyphs[TEXT_AREA].
(It only actually crashes some of the time, of course.)
^ permalink raw reply [flat|nested] 6+ messages in thread
* bug#9495: 24.0.50; Segfault in try_cursor_movement
2011-09-14 19:50 ` Johan Bockgård
@ 2011-09-15 3:12 ` Leo
2011-09-15 4:41 ` Eli Zaretskii
2011-09-15 16:05 ` Eli Zaretskii
1 sibling, 1 reply; 6+ messages in thread
From: Leo @ 2011-09-15 3:12 UTC (permalink / raw)
To: Johan Bockgård; +Cc: 9495
On 2011-09-15 03:50 +0800, Johan Bockgård wrote:
> emacs -Q -eval '(setq line-move-visual nil truncate-lines t track-eol t)'
>
> C-u 100 x RET
> y <up>
>
> At this point, in try_cursor_movement, point is in the "x" line, the
> window has not yet hscrolled, and the value of hpos is just after the
> last valid element in glyphs[TEXT_AREA].
>
> (It only actually crashes some of the time, of course.)
Does this happen with emacs-23? FWIW, I cannot get emacs-23 to crash.
Leo
^ permalink raw reply [flat|nested] 6+ messages in thread
* bug#9495: 24.0.50; Segfault in try_cursor_movement
2011-09-15 3:12 ` Leo
@ 2011-09-15 4:41 ` Eli Zaretskii
0 siblings, 0 replies; 6+ messages in thread
From: Eli Zaretskii @ 2011-09-15 4:41 UTC (permalink / raw)
To: Leo; +Cc: bojohan, 9495
> From: Leo <sdl.web@gmail.com>
> Cc: Eli Zaretskii <eliz@gnu.org>, 9495@debbugs.gnu.org
> Date: Thu, 15 Sep 2011 11:12:32 +0800
>
> On 2011-09-15 03:50 +0800, Johan Bockgård wrote:
> > emacs -Q -eval '(setq line-move-visual nil truncate-lines t track-eol t)'
> >
> > C-u 100 x RET
> > y <up>
> >
> > At this point, in try_cursor_movement, point is in the "x" line, the
> > window has not yet hscrolled, and the value of hpos is just after the
> > last valid element in glyphs[TEXT_AREA].
> >
> > (It only actually crashes some of the time, of course.)
>
> Does this happen with emacs-23? FWIW, I cannot get emacs-23 to crash.
It cannot possibly happen with Emacs 23, because this code is part of
the changes introduced in Emacs 24 for supporting display of
bidirectional text.
IOW, it's my fault ;-)
^ permalink raw reply [flat|nested] 6+ messages in thread
* bug#9495: 24.0.50; Segfault in try_cursor_movement
2011-09-14 19:50 ` Johan Bockgård
2011-09-15 3:12 ` Leo
@ 2011-09-15 16:05 ` Eli Zaretskii
1 sibling, 0 replies; 6+ messages in thread
From: Eli Zaretskii @ 2011-09-15 16:05 UTC (permalink / raw)
To: Johan Bockgård; +Cc: 9495-done
> From: Johan Bockgård <bojohan@gnu.org>
> Cc: 9495@debbugs.gnu.org
> Date: Wed, 14 Sep 2011 21:50:29 +0200
>
> emacs -Q -eval '(setq line-move-visual nil truncate-lines t track-eol t)'
>
> C-u 100 x RET
> y <up>
>
> At this point, in try_cursor_movement, point is in the "x" line, the
> window has not yet hscrolled, and the value of hpos is just after the
> last valid element in glyphs[TEXT_AREA].
>
> (It only actually crashes some of the time, of course.)
Thanks, I committed your patch with a minor variation.
^ permalink raw reply [flat|nested] 6+ messages in thread
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2011-09-13 19:28 bug#9495: 24.0.50; Segfault in try_cursor_movement Johan Bockgård
2011-09-14 5:22 ` Eli Zaretskii
2011-09-14 19:50 ` Johan Bockgård
2011-09-15 3:12 ` Leo
2011-09-15 4:41 ` Eli Zaretskii
2011-09-15 16:05 ` Eli Zaretskii
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