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Subject: PERFORCE change 186576 for review
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http://p4web.freebsd.org/@@186576?ac=10

Change 186576 by jhb@jhb_jhbbsd on 2010/12/02 22:06:51

	Revert the process back to an exec'ing thread's credentials.

Affected files ...

.. //depot/projects/smpng/sys/kern/kern_exec.c#135 edit

Differences ...

==== //depot/projects/smpng/sys/kern/kern_exec.c#135 (text+ko) ====

@@ -582,12 +582,23 @@
 	VREF(binvp);
 
 	/*
+	 * Force the process to use this thread's credentials to avoid
+	 * a race where another thread changed this process' credentials
+	 * while we were waiting for all other threads to stop.
+	 */
+	PROC_LOCK(p);
+	if (td->td_ucred != p->p_ucred) {
+		oldcred = p->p_ucred;
+		p->p_ucred = crhold(td->td_ucred);
+		crfree(oldcred);
+	}
+
+	/*
 	 * For security and other reasons, signal handlers cannot
 	 * be shared after an exec. The new process gets a copy of the old
 	 * handlers. In execsigs(), the new process will have its signals
 	 * reset.
 	 */
-	PROC_LOCK(p);
 	oldcred = crcopysafe(p, newcred);
 	if (sigacts_shared(p->p_sigacts)) {
 		oldsigacts = p->p_sigacts;
@@ -599,16 +610,6 @@
 	} else
 		oldsigacts = NULL;
 
-	/*
-	 * Ensure that this thread's credentials match the proces
-	 * credentials.
-	 */
-	if (td->td_ucred != p->p_ucred) {
-		oldcred = td->td_ucred;
-		td->td_ucred = crhold(p->p_ucred);
-		crfree(oldcred);
-	}
-
 	/* Stop profiling */
 	stopprofclock(p);