GNU bug report logs - #9495
24.0.50; Segfault in try_cursor_movement

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

From: Johan Bockgård <bojohan <at> gnu.org>
To: bug-gnu-emacs <at> gnu.org
Subject: 24.0.50; Segfault in try_cursor_movement
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


2011-09-13  Johan Bockgård  <bojohan <at> 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.

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