From: Andrew Cooper <andrew.cooper3@citrix.com>
Date: Tue, 17 Dec 2013 15:38:07 +0000 (+0100)
Subject: x86/mm: Prevent leaking domain mappings in paging_log_dirty_op()
X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~5745
X-Git-Url: https://dgit.raspbian.org/%22http:/www.example.com/cgi/%22https:/%22bookmarks://%22/%22http:/www.example.com/cgi/%22https:/%22bookmarks:/%22?a=commitdiff_plain;h=0725f326358cbb2ba7f9626976e346b963d74c37;p=xen.git

x86/mm: Prevent leaking domain mappings in paging_log_dirty_op()

Coverity ID: 1135374 1135375 1135376 1135377

If {copy_to,clear}_guest_offset() fails, we would leak the domain mappings for
l4 thru l1.

Fixing this requires having conditional unmaps on the faulting path, which in
turn requires explicitly initialising the pointers to NULL because of the
early ENOMEM exit.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <JBeulich@suse.com>
Acked-by: Tim Deegan <tim@xen.org>
---

diff --git a/xen/arch/x86/mm/paging.c b/xen/arch/x86/mm/paging.c
index 4ba7669a34..21344e50ff 100644
--- a/xen/arch/x86/mm/paging.c
+++ b/xen/arch/x86/mm/paging.c
@@ -330,8 +330,8 @@ int paging_log_dirty_op(struct domain *d, struct xen_domctl_shadow_op *sc)
 {
     int rv = 0, clean = 0, peek = 1;
     unsigned long pages = 0;
-    mfn_t *l4, *l3, *l2;
-    unsigned long *l1;
+    mfn_t *l4 = NULL, *l3 = NULL, *l2 = NULL;
+    unsigned long *l1 = NULL;
     int i4, i3, i2;
 
     domain_pause(d);
@@ -434,6 +434,16 @@ int paging_log_dirty_op(struct domain *d, struct xen_domctl_shadow_op *sc)
  out:
     paging_unlock(d);
     domain_unpause(d);
+
+    if ( l1 )
+        unmap_domain_page(l1);
+    if ( l2 )
+        unmap_domain_page(l2);
+    if ( l3 )
+        unmap_domain_page(l3);
+    if ( l4 )
+        unmap_domain_page(l4);
+
     return rv;
 }