vim-patch:9.0.2108: [security]: overflow with count for :s command

Problem:  [security]: overflow with count for :s command
Solution: Abort the :s command if the count is too large

If the count after the :s command is larger than what fits into a
(signed) long variable, abort with e_value_too_large.

Adds a test with INT_MAX as count and verify it correctly fails.

It seems the return value on Windows using mingw compiler wraps around,
so the initial test using :s/./b/9999999999999999999999999990 doesn't
fail there, since the count is wrapping around several times and finally
is no longer larger than 2147483647. So let's just use 2147483647 in the
test, which hopefully will always cause a failure

https://github.com/vim/vim/commit/ac63787734fda2e294e477af52b3bd601517fa78

Co-authored-by: Christian Brabandt <cb@256bit.org>

6 files changed, 15 insertions, 8 deletions

diff --git a/runtime/doc/change.txt b/runtime/doc/change.txt
index 2c47421b02..e1bb7c5fc7 100644
--- a/runtime/doc/change.txt
+++ b/runtime/doc/change.txt
@@ -619,9 +619,9 @@ original user.
 			current line only.  When [count] is given, replace in
 			[count] lines, starting with the last line in [range].
 			When [range] is omitted start in the current line.
-							*E939*
-			[count] must be a positive number.  Also see
-			|cmdline-ranges|.
+							*E939* *E1510*
+			[count] must be a positive number (max 2147483647)
+			Also see |cmdline-ranges|.
 
 			See |:s_flags| for [flags].
 			The delimiter doesn't need to be /, see
diff --git a/runtime/doc/cmdline.txt b/runtime/doc/cmdline.txt
index 291286d8f7..8bed8a9ffc 100644
--- a/runtime/doc/cmdline.txt
+++ b/runtime/doc/cmdline.txt
@@ -339,6 +339,7 @@ terminals)
 		A positive number represents the absolute index of an entry
 		as it is given in the first column of a :history listing.
 		This number remains fixed even if other entries are deleted.
+		(see |E1510|)
 
 		A negative number means the relative position of an entry,
 		counted from the newest entry (which has index -1) backwards.
diff --git a/src/nvim/cmdhist.c b/src/nvim/cmdhist.c
index be94c08d3a..1f1d7d2eab 100644
--- a/src/nvim/cmdhist.c
+++ b/src/nvim/cmdhist.c
@@ -30,8 +30,6 @@
 # include "cmdhist.c.generated.h"
 #endif
 
-static const char e_val_too_large[] = N_("E1510: Value too large: %s");
-
 static histentry_T *(history[HIST_COUNT]) = { NULL, NULL, NULL, NULL, NULL };
 static int hisidx[HIST_COUNT] = { -1, -1, -1, -1, -1 };  ///< lastused entry
 /// identifying (unique) number of newest history entry
diff --git a/src/nvim/ex_cmds.c b/src/nvim/ex_cmds.c
index 521f8eb208..692b320335 100644
--- a/src/nvim/ex_cmds.c
+++ b/src/nvim/ex_cmds.c
@@ -3411,10 +3411,15 @@ static int do_sub(exarg_T *eap, const proftime_T timeout, const int cmdpreview_n
   // check for a trailing count
   cmd = skipwhite(cmd);
   if (ascii_isdigit(*cmd)) {
-    i = getdigits_int(&cmd, true, 0);
+    i = getdigits_int(&cmd, true, INT_MAX);
     if (i <= 0 && !eap->skip && subflags.do_error) {
       emsg(_(e_zerocount));
       return 0;
+    } else if (i >= INT_MAX) {
+      char buf[20];
+      vim_snprintf(buf, sizeof(buf), "%d", i);
+      semsg(_(e_val_too_large), buf);
+      return 0;
     }
     eap->line1 = eap->line2;
     eap->line2 += (linenr_T)i - 1;
diff --git a/src/nvim/globals.h b/src/nvim/globals.h
index 0cab3d1f8c..8e773d691a 100644
--- a/src/nvim/globals.h
+++ b/src/nvim/globals.h
@@ -1026,11 +1026,13 @@ EXTERN const char e_highlight_group_name_too_long[] INIT(= N_("E1249: Highlight
 
 EXTERN const char e_invalid_line_number_nr[] INIT(= N_("E966: Invalid line number: %ld"));
 
-EXTERN char e_stray_closing_curly_str[]
+EXTERN const char e_stray_closing_curly_str[]
 INIT(= N_("E1278: Stray '}' without a matching '{': %s"));
-EXTERN char e_missing_close_curly_str[]
+EXTERN const char e_missing_close_curly_str[]
 INIT(= N_("E1279: Missing '}': %s"));
 
+EXTERN const char e_val_too_large[] INIT(= N_("E1510: Value too large: %s"));
+
 EXTERN const char e_undobang_cannot_redo_or_move_branch[]
 INIT(= N_("E5767: Cannot use :undo! to redo or move to a different undo branch"));
 
diff --git a/test/old/testdir/test_substitute.vim b/test/old/testdir/test_substitute.vim
index 956d51893d..75062f13aa 100644
--- a/test/old/testdir/test_substitute.vim
+++ b/test/old/testdir/test_substitute.vim
@@ -206,6 +206,7 @@ func Test_substitute_count()
   call assert_equal(['foo foo', 'foo foo', 'foo foo', 'bar foo', 'bar foo'],
         \           getline(1, '$'))
 
+  call assert_fails('s/./b/2147483647', 'E1510:')
   bwipe!
 endfunc