Use SAFE_ALLOCA etc. to avoid unbounded stack allocation.

This follows up on the recent thread in emacs-devel on alloca; see:
http://lists.gnu.org/archive/html/emacs-devel/2014-09/msg00042.html
This patch also cleans up alloca-related glitches noted while
examining the code looking for unbounded alloca.
* alloc.c (listn):
* callproc.c (init_callproc):
Rewrite to avoid need for alloca.
* buffer.c (mouse_face_overlay_overlaps)
(report_overlay_modification):
* buffer.h (GET_OVERLAYS_AT):
* coding.c (make_subsidiaries):
* doc.c (Fsnarf_documentation):
* editfns.c (Fuser_full_name):
* fileio.c (Ffile_name_directory, Fexpand_file_name)
(search_embedded_absfilename, Fsubstitute_in_file_name):
* fns.c (Fmake_hash_table):
* font.c (font_vconcat_entity_vectors, font_update_drivers):
* fontset.c (fontset_pattern_regexp, Ffontset_info):
* frame.c (Fmake_terminal_frame, x_set_frame_parameters)
(xrdb_get_resource, x_get_resource_string):
* ftfont.c (ftfont_get_charset, ftfont_check_otf, ftfont_drive_otf):
* ftxfont.c (ftxfont_draw):
* image.c (xbm_load, xpm_load, jpeg_load_body):
* keyboard.c (echo_add_key, menu_bar_items, tool_bar_items):
* keymap.c (Fdescribe_buffer_bindings, describe_map):
* lread.c (openp):
* menu.c (digest_single_submenu, find_and_call_menu_selection)
(find_and_return_menu_selection):
* print.c (PRINTFINISH):
* process.c (Fformat_network_address):
* scroll.c (do_scrolling, do_direct_scrolling, scrolling_1):
* search.c (search_buffer, Fmatch_data, Fregexp_quote):
* sound.c (wav_play, au_play):
* syntax.c (skip_chars):
* term.c (tty_menu_activate, tty_menu_show):
* textprop.c (get_char_property_and_overlay):
* window.c (Fset_window_configuration):
* xdisp.c (safe__call, next_overlay_change, vmessage)
(compute_overhangs_and_x, draw_glyphs, note_mouse_highlight):
* xfaces.c (face_at_buffer_position):
* xmenu.c (x_menu_show):
Use SAFE_ALLOCA etc. instead of plain alloca, since the
allocation size isn't bounded.
* callint.c (Fcall_interactively): Redo memory_full check
so that it can be done at compile-time on some platforms.
* coding.c (MAX_LOOKUP_MAX): New constant.
(get_translation_table): Use it.
* callproc.c (call_process): Use SAFE_NALLOCA instead of
SAFE_ALLOCA, to catch integer overflows on size calculation.
(exec_failed) [!DOS_NT]: New function.
(child_setup) [!DOS_NT]: Use it.
* editfns.c (Ftranspose_regions):
Hoist USE_SAFE_ALLOC + SAFE_FREE out of 'if'.
* editfns.c (check_translation):
Allocate larger buffers on the heap.
* eval.c (internal_lisp_condition_case):
Check for MAX_ALLOCA overflow.
* fns.c (sort_vector): Use SAFE_ALLOCA_LISP rather than Fmake_vector.
(Fbase64_encode_region, Fbase64_decode_region):
Avoid unnecessary calls to SAFE_FREE before 'error'.
* buffer.c (mouse_face_overlay_overlaps):
* editfns.c (Fget_pos_property, check_translation):
* eval.c (Ffuncall):
* font.c (font_unparse_xlfd, font_find_for_lface):
* ftfont.c (ftfont_drive_otf):
* keyboard.c (echo_add_key, read_decoded_event_from_main_queue)
(menu_bar_items, tool_bar_items):
* sound.c (Fplay_sound_internal):
* xdisp.c (load_overlay_strings, dump_glyph_row):
Use an ordinary auto buffer rather than alloca, since the
allocation size is fixed and small.
* ftfont.c: Include <c-strcase.h>.
(matching_prefix): New function.
(get_adstyle_property): Use it, to avoid need for alloca.
* keyboard.c (echo_add_key):
* keymap.c (describe_map): Use ptrdiff_t, not int.
* keyboard.c (echo_add_key): Prefer sizeof to strlen.
* keymap.c (Fdescribe_buffer_bindings): Use SBYTES, not SCHARS,
when counting bytes.
* lisp.h (xlispstrdupa): Remove, replacing with ...
(SAFE_ALLOCA_STRING): ... new macro with different API.
This fixes a portability problem, namely, alloca result
passed to another function.  All uses changed.
(SAFE_ALLOCA, SAFE_ALLOCA_LISP): Check for MAX_ALLOCA,
not MAX_ALLOCA - 1.
* regex.c (REGEX_USE_SAFE_ALLOCA, REGEX_SAFE_FREE)
(REGEX_ALLOCATE): New macros.
(REGEX_REALLOCATE, REGEX_ALLOCATE_STACK, REGEX_REALLOCATE_STACK)
(REGEX_FREE_STACK, FREE_VARIABLES, re_match_2_internal):
Use them.
* xdisp.c (message3): Use SAFE_ALLOCA_STRING rather than doing it
by hand.
(decode_mode_spec_coding): Store directly into buf rather than
into an alloca temporary and copying the temporary to the buf.

Fixes: debbugs:18410

1 files changed, 19 insertions, 9 deletions

diff --git a/src/scroll.c b/src/scroll.c
index 6c559663f80..7cb683c4577 100644
--- a/src/scroll.c
+++ b/src/scroll.c
@@ -245,18 +245,20 @@ do_scrolling (struct frame *frame, struct glyph_matrix *current_matrix,
 {
   struct matrix_elt *p;
   int i, j, k;
+  USE_SAFE_ALLOCA;
 
   /* True if we have set a terminal window with set_terminal_window.  */
   bool terminal_window_p = 0;
 
   /* A queue for line insertions to be done.  */
   struct queue { int count, pos; };
-  struct queue *queue_start
-    = alloca (current_matrix->nrows * sizeof *queue_start);
+  struct queue *queue_start;
+  SAFE_NALLOCA (queue_start, 1, current_matrix->nrows);
   struct queue *queue = queue_start;
 
-  char *retained_p = alloca (window_size * sizeof *retained_p);
-  int *copy_from = alloca (window_size * sizeof *copy_from);
+  char *retained_p = SAFE_ALLOCA (window_size);
+  int *copy_from;
+  SAFE_NALLOCA (copy_from, 1, window_size);
 
   /* Zero means line is empty.  */
   memset (retained_p, 0, window_size * sizeof (char));
@@ -378,6 +380,7 @@ do_scrolling (struct frame *frame, struct glyph_matrix *current_matrix,
 
   if (terminal_window_p)
     set_terminal_window (frame, 0);
+  SAFE_FREE ();
 }
 
 
@@ -649,10 +652,12 @@ do_direct_scrolling (struct frame *frame, struct glyph_matrix *current_matrix,
 {
   struct matrix_elt *p;
   int i, j;
+  USE_SAFE_ALLOCA;
 
   /* A queue of deletions and insertions to be performed.  */
   struct alt_queue { int count, pos, window; };
-  struct alt_queue *queue_start = alloca (window_size * sizeof *queue_start);
+  struct alt_queue *queue_start;
+  SAFE_NALLOCA (queue_start, 1, window_size);
   struct alt_queue *queue = queue_start;
 
   /* True if a terminal window has been set with set_terminal_window.  */
@@ -667,11 +672,12 @@ do_direct_scrolling (struct frame *frame, struct glyph_matrix *current_matrix,
   bool write_follows_p = 1;
 
   /* For each row in the new matrix what row of the old matrix it is.  */
-  int *copy_from = alloca (window_size * sizeof *copy_from);
+  int *copy_from;
+  SAFE_NALLOCA (copy_from, 1, window_size);
 
   /* Non-zero for each row in the new matrix that is retained from the
      old matrix.  Lines not retained are empty.  */
-  char *retained_p = alloca (window_size * sizeof *retained_p);
+  char *retained_p = SAFE_ALLOCA (window_size);
 
   memset (retained_p, 0, window_size * sizeof (char));
 
@@ -787,6 +793,7 @@ do_direct_scrolling (struct frame *frame, struct glyph_matrix *current_matrix,
 
   if (terminal_window_p)
     set_terminal_window (frame, 0);
+  SAFE_FREE ();
 }
 
 
@@ -796,8 +803,9 @@ scrolling_1 (struct frame *frame, int window_size, int unchanged_at_top,
              int unchanged_at_bottom, int *draw_cost, int *old_draw_cost,
              unsigned *old_hash, unsigned *new_hash, int free_at_end)
 {
-  struct matrix_elt *matrix
-    = alloca ((window_size + 1) * (window_size + 1) * sizeof *matrix);
+  USE_SAFE_ALLOCA;
+  struct matrix_elt *matrix;
+  SAFE_NALLOCA (matrix, window_size + 1, window_size + 1);
 
   if (FRAME_SCROLL_REGION_OK (frame))
     {
@@ -817,6 +825,8 @@ scrolling_1 (struct frame *frame, int window_size, int unchanged_at_top,
                     frame->current_matrix, matrix, window_size,
                     unchanged_at_top);
     }
+
+  SAFE_FREE ();
 }