[Xen-changelog] [xen stable-4.4] mm: populate_physmap: validate correctly the gfn for direct mapped domain

[patchbot@xxxxxxx]

commit e554ae491d780435713381e43deb8356083be3ee
Author:     Julien Grall <julien.grall@xxxxxxxxxx>
AuthorDate: Thu Sep 10 15:56:03 2015 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Thu Sep 10 15:56:03 2015 +0200

    mm: populate_physmap: validate correctly the gfn for direct mapped domain
    
    Direct mapped domain has already the memory allocated 1:1, so we are
    directly using the gfn as mfn to map the RAM in the guest.
    
    While we are validating that the page associated to the first mfn belongs to
    the domain, the subsequent MFN are not validated when the extent_order
    is > 0.
    
    This may result to map memory region (MMIO, RAM) which doesn't belong to the
    domain.
    
    Although, only DOM0 on ARM is using a direct memory mapped. So it
    doesn't affect any guest (at least on the upstream version) or even x86.
    
    Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
    Release-acked-by: Wei Liu <wei.liu2@xxxxxxxxxx>
    Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
    master commit: 9503ab0e9c6a41a1ee7a70c8ea9313d08ebaa8c5
    master date: 2015-08-13 14:41:09 +0200
---
 xen/common/memory.c |   32 +++++++++++++++++++-------------
 1 files changed, 19 insertions(+), 13 deletions(-)

diff --git a/xen/common/memory.c b/xen/common/memory.c
index 38f79b3..701c5fb 100644
--- a/xen/common/memory.c
+++ b/xen/common/memory.c
@@ -129,22 +129,28 @@ static void populate_physmap(struct memop_args *a)
             if ( is_domain_direct_mapped(d) )
             {
                 mfn = gpfn;
-                if ( !mfn_valid(mfn) )
-                {
-                    gdprintk(XENLOG_INFO, "Invalid mfn %#"PRI_xen_pfn"\n",
-                             mfn);
-                    goto out;
-                }
 
-                page = mfn_to_page(mfn);
-                if ( !get_page(page, d) )
+                for ( j = 0; j < (1U << a->extent_order); j++, mfn++ )
                 {
-                    gdprintk(XENLOG_INFO,
-                             "mfn %#"PRI_xen_pfn" doesn't belong to the"
-                             " domain\n", mfn);
-                    goto out;
+                    if ( !mfn_valid(mfn) )
+                    {
+                        gdprintk(XENLOG_INFO, "Invalid mfn %#"PRI_xen_pfn"\n",
+                                 mfn);
+                        goto out;
+                    }
+
+                    page = mfn_to_page(mfn);
+                    if ( !get_page(page, d) )
+                    {
+                        gdprintk(XENLOG_INFO,
+                                 "mfn %#"PRI_xen_pfn" doesn't belong to the"
+                                 " domain\n", mfn);
+                        goto out;
+                    }
+                    put_page(page);
                 }
-                put_page(page);
+
+                page = mfn_to_page(gpfn);
             }
             else
                 page = alloc_domheap_pages(d, a->extent_order, a->memflags);
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.4

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