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From: Gleb Smirnoff <glebius@FreeBSD.org>
Date: Tue, 4 Jun 2013 11:19:09 +0000 (UTC)
To: src-committers@freebsd.org, svn-src-all@freebsd.org,
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Subject: svn commit: r251374 - head/sys/kern
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Author: glebius
Date: Tue Jun  4 11:19:08 2013
New Revision: 251374
URL: http://svnweb.freebsd.org/changeset/base/251374

Log:
  Improve r250890, so that we stop processing of a message with zero
  descriptors as early as possible, and assert that number of descriptors
  is positive in unp_freerights().
  
  Reviewed by:	mjg, pjd, jilles

Modified:
  head/sys/kern/uipc_usrreq.c

Modified: head/sys/kern/uipc_usrreq.c
==============================================================================
--- head/sys/kern/uipc_usrreq.c	Tue Jun  4 11:05:57 2013	(r251373)
+++ head/sys/kern/uipc_usrreq.c	Tue Jun  4 11:19:08 2013	(r251374)
@@ -1686,8 +1686,8 @@ unp_freerights(struct filedescent **fdep
 	struct file *fp;
 	int i;
 
-	if (fdcount == 0)
-		return;
+	KASSERT(fdcount > 0, ("%s: fdcount %d", __func__, fdcount));
+
 	for (i = 0; i < fdcount; i++) {
 		fp = fdep[i]->fde_file;
 		filecaps_free(&fdep[i]->fde_caps);
@@ -1725,6 +1725,8 @@ unp_externalize(struct mbuf *control, st
 		if (cm->cmsg_level == SOL_SOCKET
 		    && cm->cmsg_type == SCM_RIGHTS) {
 			newfds = datalen / sizeof(*fdep);
+			if (newfds == 0)
+				goto next;
 			fdep = data;
 
 			/* If we're not outputting the descriptors free them. */
@@ -1770,8 +1772,7 @@ unp_externalize(struct mbuf *control, st
 				unp_externalize_fp(fde->fde_file);
 			}
 			FILEDESC_XUNLOCK(fdesc);
-			if (newfds != 0)
-				free(fdep[0], M_FILECAPS);
+			free(fdep[0], M_FILECAPS);
 		} else {
 			/* We can just copy anything else across. */
 			if (error || controlp == NULL)
@@ -1894,6 +1895,8 @@ unp_internalize(struct mbuf **controlp, 
 
 		case SCM_RIGHTS:
 			oldfds = datalen / sizeof (int);
+			if (oldfds == 0)
+				break;
 			/*
 			 * Check that all the FDs passed in refer to legal
 			 * files.  If not, reject the entire operation.
@@ -1928,10 +1931,6 @@ unp_internalize(struct mbuf **controlp, 
 				error = E2BIG;
 				goto out;
 			}
-			if (oldfds == 0) {
-				FILEDESC_SUNLOCK(fdesc);
-				break;
-			}
 			fdp = data;
 			fdep = (struct filedescent **)
 			    CMSG_DATA(mtod(*controlp, struct cmsghdr *));