svn commit: r316852 - head/sbin/fsck_ffs

[Konstantin Belousov]

Author: kib
Date: Fri Apr 14 15:22:00 2017
New Revision: 316852
URL: https://svnweb.freebsd.org/changeset/base/316852

Log:
  In fsck_ffs pass1, prevent the inosused variable from wrapping.
  
  The loop that scans the used inode map when soft updates is in use
  assumes that the inosused variable is signed.  However, ino_t is
  unsigned, so the loop invariant is incorrect and the check for
  inosused wrapping to < 0 can never be true.
  
  Instead of checking for wrap after the fact just prevent it from
  happening in the first place.
  
  PR:	218592
  Submitted by:	Todd Miller <todd.miller at courtesan.com>
  Reviewed by:	mckusick
  MFC after:	1 week

Modified:
  head/sbin/fsck_ffs/pass1.c

Modified: head/sbin/fsck_ffs/pass1.c
==============================================================================
--- head/sbin/fsck_ffs/pass1.c	Fri Apr 14 15:16:41 2017	(r316851)
+++ head/sbin/fsck_ffs/pass1.c	Fri Apr 14 15:22:00 2017	(r316852)
@@ -133,9 +133,14 @@ pass1(void)
 		 */
 		if ((preen || inoopt) && usedsoftdep && !rebuildcg) {
 			cp = &cg_inosused(cgp)[(inosused - 1) / CHAR_BIT];
-			for ( ; inosused > 0; inosused -= CHAR_BIT, cp--) {
-				if (*cp == 0)
+			for ( ; inosused != 0; cp--) {
+				if (*cp == 0) {
+					if (inosused > CHAR_BIT)
+						inosused -= CHAR_BIT;
+					else
+						inosused = 0;
 					continue;
+				}
 				for (i = 1 << (CHAR_BIT - 1); i > 0; i >>= 1) {
 					if (*cp & i)
 						break;
@@ -143,8 +148,6 @@ pass1(void)
 				}
 				break;
 			}
-			if (inosused < 0)
-				inosused = 0;
 		}
 		/*
 		 * Allocate inoinfo structures for the allocated inodes.