(main): Check for overflow in tabstop values

specified via the obsolete form.  E.g., now this command fails:
_POSIX2_VERSION=1 ./unexpand -$(echo '2^64+1'|bc)
Before it would act like `_POSIX2_VERSION=1 ./unexpand -1'.

1 files changed, 6 insertions, 1 deletions

diff --git a/src/unexpand.c b/src/unexpand.c
index 1341e437c..60a3f1d61 100644
--- a/src/unexpand.c
+++ b/src/unexpand.c
@@ -518,7 +518,12 @@ main (int argc, char **argv)
 	      tabval = 0;
 	      have_tabval = true;
 	    }
-	  tabval = tabval * 10 + c - '0';
+	  {
+	    uintmax_t new_t = tabval * 10 + c - '0';
+	    if (UINTMAX_MAX / 10 < tabval || new_t < tabval * 10)
+	      error (EXIT_FAILURE, 0, _("tab stop value is too large"));
+	    tabval = new_t;
+	  }
 	  obsolete_tablist = true;
 	  break;
 	}