patch 9.0.2122: [security]: prevent overflow in indentingv9.0.2122

Problem:  [security]: prevent overflow in indenting
Solution: use long long and remove cast to (int)

The shiftwidth option values are defined as being long. However, when
calculating the actual amount of indent, we cast down to (int), which
may cause the shiftwidth value to become negative and later it may even
cause Vim to try to allocate a huge amount of memory.

We already use long and long long variable types to calculate the indent
(and detect possible overflows), so the cast to (int) seems superfluous
and can be safely removed. So let's just remove the (int) cast and
calculate the indent using longs.

Additionally, the 'shiftwidth' option value is also used when determining
the actual 'cino' options. There it can again cause another overflow, so
make sure it is safe in parse_cino() as well.

fixes: #13554
closes: #13555

Signed-off-by: Christian Brabandt <cb@256bit.org>

1 files changed, 51 insertions, 39 deletions

diff --git a/src/cindent.c b/src/cindent.c
index 9b2b6442a6..7ac1f4ba87 100644
--- a/src/cindent.c
+++ b/src/cindent.c
@@ -1730,10 +1730,17 @@ parse_cino(buf_T *buf)
     char_u	*p;
     char_u	*l;
     char_u	*digits;
-    int		n;
+    long long	n;
     int		divider;
     int		fraction = 0;
-    int		sw = (int)get_sw_value(buf);
+    int		sw;
+    long long	t = get_sw_value(buf);
+
+    // needed for cino-(, it will be multiplied by 2 again
+    if (t > INT_MAX / 2)
+	sw = INT_MAX / 2;
+    else
+	sw = (int)t;
 
     // Set the default values.
 
@@ -1902,47 +1909,52 @@ parse_cino(buf_T *buf)
 	if (l[1] == '-')
 	    n = -n;
 
+	if (n > INT_MAX)
+	    n = INT_MAX;
+	else if (n < INT_MIN)
+	    n = INT_MIN;
+
 	// When adding an entry here, also update the default 'cinoptions' in
 	// doc/indent.txt, and add explanation for it!
 	switch (*l)
 	{
-	    case '>': buf->b_ind_level = n; break;
-	    case 'e': buf->b_ind_open_imag = n; break;
-	    case 'n': buf->b_ind_no_brace = n; break;
-	    case 'f': buf->b_ind_first_open = n; break;
-	    case '{': buf->b_ind_open_extra = n; break;
-	    case '}': buf->b_ind_close_extra = n; break;
-	    case '^': buf->b_ind_open_left_imag = n; break;
-	    case 'L': buf->b_ind_jump_label = n; break;
-	    case ':': buf->b_ind_case = n; break;
-	    case '=': buf->b_ind_case_code = n; break;
-	    case 'b': buf->b_ind_case_break = n; break;
-	    case 'p': buf->b_ind_param = n; break;
-	    case 't': buf->b_ind_func_type = n; break;
-	    case '/': buf->b_ind_comment = n; break;
-	    case 'c': buf->b_ind_in_comment = n; break;
-	    case 'C': buf->b_ind_in_comment2 = n; break;
-	    case 'i': buf->b_ind_cpp_baseclass = n; break;
-	    case '+': buf->b_ind_continuation = n; break;
-	    case '(': buf->b_ind_unclosed = n; break;
-	    case 'u': buf->b_ind_unclosed2 = n; break;
-	    case 'U': buf->b_ind_unclosed_noignore = n; break;
-	    case 'W': buf->b_ind_unclosed_wrapped = n; break;
-	    case 'w': buf->b_ind_unclosed_whiteok = n; break;
-	    case 'm': buf->b_ind_matching_paren = n; break;
-	    case 'M': buf->b_ind_paren_prev = n; break;
-	    case ')': buf->b_ind_maxparen = n; break;
-	    case '*': buf->b_ind_maxcomment = n; break;
-	    case 'g': buf->b_ind_scopedecl = n; break;
-	    case 'h': buf->b_ind_scopedecl_code = n; break;
-	    case 'j': buf->b_ind_java = n; break;
-	    case 'J': buf->b_ind_js = n; break;
-	    case 'l': buf->b_ind_keep_case_label = n; break;
-	    case '#': buf->b_ind_hash_comment = n; break;
-	    case 'N': buf->b_ind_cpp_namespace = n; break;
-	    case 'k': buf->b_ind_if_for_while = n; break;
-	    case 'E': buf->b_ind_cpp_extern_c = n; break;
-	    case 'P': buf->b_ind_pragma = n; break;
+	    case '>': buf->b_ind_level = (int)n; break;
+	    case 'e': buf->b_ind_open_imag = (int)n; break;
+	    case 'n': buf->b_ind_no_brace = (int)n; break;
+	    case 'f': buf->b_ind_first_open = (int)n; break;
+	    case '{': buf->b_ind_open_extra = (int)n; break;
+	    case '}': buf->b_ind_close_extra = (int)n; break;
+	    case '^': buf->b_ind_open_left_imag = (int)n; break;
+	    case 'L': buf->b_ind_jump_label = (int)n; break;
+	    case ':': buf->b_ind_case = (int)n; break;
+	    case '=': buf->b_ind_case_code = (int)n; break;
+	    case 'b': buf->b_ind_case_break = (int)n; break;
+	    case 'p': buf->b_ind_param = (int)n; break;
+	    case 't': buf->b_ind_func_type = (int)n; break;
+	    case '/': buf->b_ind_comment = (int)n; break;
+	    case 'c': buf->b_ind_in_comment = (int)n; break;
+	    case 'C': buf->b_ind_in_comment2 = (int)n; break;
+	    case 'i': buf->b_ind_cpp_baseclass = (int)n; break;
+	    case '+': buf->b_ind_continuation = (int)n; break;
+	    case '(': buf->b_ind_unclosed = (int)n; break;
+	    case 'u': buf->b_ind_unclosed2 = (int)n; break;
+	    case 'U': buf->b_ind_unclosed_noignore = (int)n; break;
+	    case 'W': buf->b_ind_unclosed_wrapped = (int)n; break;
+	    case 'w': buf->b_ind_unclosed_whiteok = (int)n; break;
+	    case 'm': buf->b_ind_matching_paren = (int)n; break;
+	    case 'M': buf->b_ind_paren_prev = (int)n; break;
+	    case ')': buf->b_ind_maxparen = (int)n; break;
+	    case '*': buf->b_ind_maxcomment = (int)n; break;
+	    case 'g': buf->b_ind_scopedecl = (int)n; break;
+	    case 'h': buf->b_ind_scopedecl_code = (int)n; break;
+	    case 'j': buf->b_ind_java = (int)n; break;
+	    case 'J': buf->b_ind_js = (int)n; break;
+	    case 'l': buf->b_ind_keep_case_label = (int)n; break;
+	    case '#': buf->b_ind_hash_comment = (int)n; break;
+	    case 'N': buf->b_ind_cpp_namespace = (int)n; break;
+	    case 'k': buf->b_ind_if_for_while = (int)n; break;
+	    case 'E': buf->b_ind_cpp_extern_c = (int)n; break;
+	    case 'P': buf->b_ind_pragma = (int)n; break;
 	}
 	if (*p == ',')
 	    ++p;