When reallocating the line buffer, double the existing buffer

size instead of just incrementing it by LINEBUF_SIZE and use realloc()
+ memset() instead of calloc() + memcpy().  Prevents excessive resource
usage when displaying very long lines.  OK deraadt@, krw@ and otto@

1 files changed, 5 insertions, 7 deletions

diff --git a/usr.bin/less/line.c b/usr.bin/less/line.c
index bb9caa6e18a..07858120eb0 100644
--- a/usr.bin/less/line.c
+++ b/usr.bin/less/line.c
@@ -79,9 +79,9 @@ init_line()
  	static int
 expand_linebuf()
 {
-	int new_size = size_linebuf + LINEBUF_SIZE;
-	char *new_buf = (char *) calloc(new_size, sizeof(char));
-	char *new_attr = (char *) calloc(new_size, sizeof(char));
+	int new_size = size_linebuf * 2;
+	char *new_buf = (char *) realloc(linebuf, new_size);
+	char *new_attr = (char *) realloc(attr, new_size);
 	if (new_buf == NULL || new_attr == NULL)
 	{
 		if (new_attr != NULL)
@@ -90,10 +90,8 @@ expand_linebuf()
 			free(new_buf);
 		return 1;
 	}
-	memcpy(new_buf, linebuf, size_linebuf * sizeof(char));
-	memcpy(new_attr, attr, size_linebuf * sizeof(char));
-	free(attr);
-	free(linebuf);
+	memset(new_buf + size_linebuf, 0, new_size - size_linebuf);
+	memset(new_attr + size_linebuf, 0, new_size - size_linebuf);
 	linebuf = new_buf;
 	attr = new_attr;
 	size_linebuf = new_size;