Index: sys/kern/kern_prot.c
===================================================================
--- sys/kern/kern_prot.c
+++ sys/kern/kern_prot.c
@@ -89,6 +89,8 @@
 static void crfree_final(struct ucred *cr);
 static void crsetgroups_locked(struct ucred *cr, int ngrp,
     gid_t *groups);
+static void crsortgroups(struct ucred *cr);
+static void crcopy_withoutgroups(struct ucred *dest, struct ucred *src);
 
 #ifndef _SYS_SYSPROTO_H_
 struct getpid_args {
@@ -832,7 +834,8 @@
 	newcred = crget();
 	crextend(newcred, ngrp);
 	PROC_LOCK(p);
-	oldcred = crcopysafe(p, newcred);
+	oldcred = p->p_ucred;
+	crcopy_withoutgroups(newcred, oldcred);
 
 #ifdef MAC
 	error = mac_cred_check_setgroups(oldcred, ngrp, groups);
@@ -854,6 +857,7 @@
 		newcred->cr_ngroups = 1;
 	} else {
 		crsetgroups_locked(newcred, ngrp, groups);
+		crsortgroups(newcred);
 	}
 	setsugid(p);
 	proc_set_cred(p, newcred);
@@ -2095,17 +2099,31 @@
  */
 void
 crcopy(struct ucred *dest, struct ucred *src)
+{
+
+	KASSERT(dest->cr_ref == 1, ("crcopy of shared ucred"));
+	crextend(dest, src->cr_ngroups);
+	crcopy_withoutgroups(dest, src);
+	crsetgroups_locked(dest, src->cr_ngroups, src->cr_groups);
+}
+
+static void
+crcopy_withoutgroups(struct ucred *dest, struct ucred *src)
 {
 
 	KASSERT(dest->cr_ref == 1, ("crcopy of shared ucred"));
 	bcopy(&src->cr_startcopy, &dest->cr_startcopy,
 	    (unsigned)((caddr_t)&src->cr_endcopy -
 		(caddr_t)&src->cr_startcopy));
-	crsetgroups(dest, src->cr_ngroups, src->cr_groups);
 	uihold(dest->cr_uidinfo);
 	uihold(dest->cr_ruidinfo);
 	prison_hold(dest->cr_prison);
 	loginclass_hold(dest->cr_loginclass);
+	/*
+	 * Preserve the egid
+	 */
+	dest->cr_ngroups = 1;
+	dest->cr_groups[0] = src->cr_groups[0];
 #ifdef AUDIT
 	audit_cred_copy(src, dest);
 #endif
@@ -2275,32 +2293,36 @@
 }
 
 /*
- * Copy groups in to a credential, preserving any necessary invariants.
- * Currently this includes the sorting of all supplemental gids.
+ * Copy groups in to a credential, _does_not_ sort groups.
  * crextend() must have been called before hand to ensure sufficient
  * space is available.
  */
 static void
 crsetgroups_locked(struct ucred *cr, int ngrp, gid_t *groups)
 {
-	int i;
-	int j;
-	gid_t g;
-
 	KASSERT(cr->cr_agroups >= ngrp, ("cr_ngroups is too small"));
 
 	bcopy(groups, cr->cr_groups, ngrp * sizeof(gid_t));
 	cr->cr_ngroups = ngrp;
+}
+
+/*
+ * Sort all groups except cr_groups[0] to allow groupmember to
+ * perform a binary search.
+ */
+static void
+crsortgroups(struct ucred *cr)
+{
+	int i;
+	int j;
+	gid_t g;
 
 	/*
-	 * Sort all groups except cr_groups[0] to allow groupmember to
-	 * perform a binary search.
-	 *
 	 * XXX: If large numbers of groups become common this should
 	 * be replaced with shell sort like linux uses or possibly
 	 * heap sort.
 	 */
-	for (i = 2; i < ngrp; i++) {
+	for (i = 2; i < cr->cr_ngroups; i++) {
 		g = cr->cr_groups[i];
 		for (j = i-1; j >= 1 && g < cr->cr_groups[j]; j--)
 			cr->cr_groups[j + 1] = cr->cr_groups[j];
@@ -2309,7 +2331,9 @@
 }
 
 /*
- * Copy groups in to a credential after expanding it if required.
+ * Copy groups in to a credential after expanding it if required,
+ * preserving any necessary invariants.
+ * Currently this includes the sorting of all supplemental gids.
  * Truncate the list to (ngroups_max + 1) if it is too large.
  */
 void
@@ -2321,6 +2345,7 @@
 
 	crextend(cr, ngrp);
 	crsetgroups_locked(cr, ngrp, groups);
+	crsortgroups(cr);
 }
 
 /*