From: Thomas Veerman <thomas@minix3.org>
Date: Wed, 14 Nov 2012 13:24:53 +0000 (+0000)
Subject: VFS: fix TOCTOU bug in sync
X-Git-Tag: v3.2.1~229
X-Git-Url: http://zhaoyanbai.com/repos/%22http:/www.isc.org/icons/Bv9ARM.ch13.html?a=commitdiff_plain;h=14e470be81ad5ba79b74f9ccd54bcbdcf15622c5;p=minix.git

VFS: fix TOCTOU bug in sync
---

diff --git a/servers/vfs/misc.c b/servers/vfs/misc.c
index f32ec88e2..cd7319f46 100644
--- a/servers/vfs/misc.c
+++ b/servers/vfs/misc.c
@@ -299,13 +299,13 @@ int do_sync()
   int r = OK;
 
   for (vmp = &vmnt[0]; vmp < &vmnt[NR_MNTS]; ++vmp) {
+	if ((r = lock_vmnt(vmp, VMNT_EXCL)) != OK)
+		break;
 	if (vmp->m_dev != NO_DEV && vmp->m_fs_e != NONE &&
 		 vmp->m_root_node != NULL) {
-		if ((r = lock_vmnt(vmp, VMNT_EXCL)) != OK)
-			break;
 		req_sync(vmp->m_fs_e);
-		unlock_vmnt(vmp);
 	}
+	unlock_vmnt(vmp);
   }
 
   return(r);