0101-top: Check width and col.

Otherwise they may lead to out-of-bounds writes (snprintf() returns the
number of characters which would have been written if enough space had
been available).

Also, make sure buf is null-terminated after COLPLUSCH has been written.

diff --git a/top/top.c b/top/top.c
index 83bb603b0c7ebfddb2298b95e1444774a1d0501a..5939ea889fda2be97f4c722ecb20e3473d0ab020 100644 (file)
--- a/top/top.c
+++ b/top/top.c
@@ -168,7 +168,7 @@ static float        Frame_etscale;     // so we can '*' vs. '/' WHEN 'pcpu'
 static int Autox_array [EU_MAXPFLGS],
            Autox_found;
 #define AUTOX_NO      EU_MAXPFLGS
-#define AUTOX_COL(f)  if (EU_MAXPFLGS > f) Autox_array[f] = Autox_found = 1
+#define AUTOX_COL(f)  if (EU_MAXPFLGS > f && f >= 0) Autox_array[f] = Autox_found = 1
 #define AUTOX_MODE   (0 > Rc.fixed_widest)
 
         /* Support for scale_mem and scale_num (to avoid duplication. */
@@ -1441,7 +1441,10 @@ static inline const char *make_num (long num, int width, int justr, int col, int
       goto end_justifies;
 
    if (width < snprintf(buf, sizeof(buf), "%ld", num)) {
+      if (width <= 0 || (size_t)width >= sizeof(buf))
+         width = sizeof(buf)-1;
       buf[width-1] = COLPLUSCH;
+      buf[width] = '\0';
       AUTOX_COL(col);
    }
 end_justifies:
@@ -1456,7 +1459,10 @@ static inline const char *make_str (const char *str, int width, int justr, int c
    static char buf[SCREENMAX];
 
    if (width < snprintf(buf, sizeof(buf), "%s", str)) {
+      if (width <= 0 || (size_t)width >= sizeof(buf))
+         width = sizeof(buf)-1;
       buf[width-1] = COLPLUSCH;
+      buf[width] = '\0';
       AUTOX_COL(col);
    }
    return justify_pad(buf, width, justr);