[PATCH 3.18 03/16] lib/cmdline.c: fix get_options() overflow while parsing ranges

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

3.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ilya Matveychikov <matvejchikov@gmail.com>

commit a91e0f680bcd9e10c253ae8b62462a38bd48f09f upstream.

When using get_options() it's possible to specify a range of numbers,
like 1-100500.  The problem is that it doesn't track array size while
calling internally to get_range() which iterates over the range and
fills the memory with numbers.

Link: http://lkml.kernel.org/r/2613C75C-B04D-4BFF-82A6-12F97BA0F620@gmail.com
Signed-off-by: Ilya V. Matveychikov <matvejchikov@gmail.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 lib/cmdline.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/lib/cmdline.c
+++ b/lib/cmdline.c
@@ -22,14 +22,14 @@
  *	the values[M, M+1, ..., N] into the ints array in get_options.
  */
 
-static int get_range(char **str, int *pint)
+static int get_range(char **str, int *pint, int n)
 {
 	int x, inc_counter, upper_range;
 
 	(*str)++;
 	upper_range = simple_strtol((*str), NULL, 0);
 	inc_counter = upper_range - *pint;
-	for (x = *pint; x < upper_range; x++)
+	for (x = *pint; n && x < upper_range; x++, n--)
 		*pint++ = x;
 	return inc_counter;
 }
@@ -96,7 +96,7 @@ char *get_options(const char *str, int n
 			break;
 		if (res == 3) {
 			int range_nums;
-			range_nums = get_range((char **)&str, ints + i);
+			range_nums = get_range((char **)&str, ints + i, nints - i);
 			if (range_nums < 0)
 				break;
 			/*