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From: John Baldwin <jhb@FreeBSD.org>
Date: Thu, 10 Sep 2009 12:58:38 +0000 (UTC)
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Subject: svn commit: r197062 - head/sys/dev/syscons/daemon
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Author: jhb
Date: Thu Sep 10 12:58:37 2009
New Revision: 197062
URL: http://svn.freebsd.org/changeset/base/197062

Log:
  Don't malloc a buffer while holding the prison0 mutex.  Instead, use a loop
  where we figure out the hostname length under the lock, malloc the buffer
  with the lock dropped, then recheck the length under the lock and loop again
  if the buffer is now too small.
  
  Tested by:	Norbert Koch  nkoch  demig de
  MFC after:	3 days

Modified:
  head/sys/dev/syscons/daemon/daemon_saver.c

Modified: head/sys/dev/syscons/daemon/daemon_saver.c
==============================================================================
--- head/sys/dev/syscons/daemon/daemon_saver.c	Thu Sep 10 12:55:09 2009	(r197061)
+++ head/sys/dev/syscons/daemon/daemon_saver.c	Thu Sep 10 12:58:37 2009	(r197062)
@@ -351,11 +351,23 @@ daemon_saver(video_adapter_t *adp, int b
 static int
 daemon_init(video_adapter_t *adp)
 {
+	size_t hostlen;
 
 	mtx_lock(&prison0.pr_mtx);
-	messagelen = strlen(prison0.pr_hostname) + 3 + strlen(ostype) + 1 + 
-	    strlen(osrelease);
-	message = malloc(messagelen + 1, M_DEVBUF, M_WAITOK);
+	for (;;) {
+		hostlen = strlen(prison0.pr_hostname);
+		mtx_unlock(&prison0.pr_mtx);
+	
+		messagelen = hostlen + 3 + strlen(ostype) + 1 +
+		    strlen(osrelease);
+		message = malloc(messagelen + 1, M_DEVBUF, M_WAITOK);
+		mtx_lock(&prison0.pr_mtx);
+		if (hostlen < strlen(prison0.pr_hostname)) {
+			free(message, M_DEVBUF);
+			continue;
+		}
+		break;
+	}
 	sprintf(message, "%s - %s %s", prison0.pr_hostname, ostype, osrelease);
 	mtx_unlock(&prison0.pr_mtx);
 	blanked = 0;