From: John Lo <loj@cisco.com>
Date: Wed, 4 Jul 2018 20:27:59 +0000 (-0400)
Subject: Fix clib_bitmap_next_clear() function when no clear bits left
X-Git-Tag: v18.07-rc1~51
X-Git-Url: https://gerrit.fd.io/r/gitweb?a=commitdiff_plain;h=ef8db3679746792403589fb54fa0bbb9e13245dd;p=vpp.git

Fix clib_bitmap_next_clear() function when no clear bits left

If the bitmap has no bit clear after the input bit position i,
the function will return i even if its bit is set.
Fix is to return the next bit just beyond the free bitmap.

This can cause IP neighbor scan crash in ip_neighbor_scan() with
a debug image. With production image, ip_neighbor_scan() may still
function, AFAICT, with extra neighbor delete attempts for entries
already deleted, until these entries are reused for new neighbors.

Change-Id: If6422ef6f63908ea39651de4ccbd8cb0b294bd69
Signed-off-by: John Lo <loj@cisco.com>
---

diff --git a/src/vppinfra/bitmap.h b/src/vppinfra/bitmap.h
index d6dfe86da0b..0e94d028ee3 100644
--- a/src/vppinfra/bitmap.h
+++ b/src/vppinfra/bitmap.h
@@ -728,6 +728,9 @@ clib_bitmap_next_clear (uword * ai, uword i)
 	  if (t)
 	    return log2_first_set (t) + i0 * BITS (ai[0]);
 	}
+
+      /* no clear bit left in bitmap, return bit just beyond bitmap */
+      return (i0 + 1) * BITS (ai[0]);
     }
   return i;
 }