From: Andrew Cooper <andrew.cooper3@citrix.com>
Date: Mon, 3 Aug 2015 17:05:43 +0000 (+0100)
Subject: x86/gdt: Drop write-only, xalloc()'d array from set_gdt()
X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~2654
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=a7bd9b1661304500cd18b7d216d616ecf053ebdb;p=xen.git

x86/gdt: Drop write-only, xalloc()'d array from set_gdt()

It is not used, and can cause a spurious failure of the set_gdt() hypercall in
low memory situations.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
Reviewed-by: Ian Campbell <ian.campbell@citrix.com>
Reviewed-by: George Dunlap <george.dunlap@eu.citrix.com>
---

diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index 63aa666770..4b76587d42 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -4439,20 +4439,15 @@ long set_gdt(struct vcpu *v,
     l1_pgentry_t *pl1e;
     /* NB. There are 512 8-byte entries per GDT page. */
     int i, nr_pages = (entries + 511) / 512;
-    unsigned long *pfns;
 
     if ( entries > FIRST_RESERVED_GDT_ENTRY )
         return -EINVAL;
 
-    pfns = xmalloc_array(unsigned long, nr_pages);
-    if ( !pfns )
-        return -ENOMEM;
-
     /* Check the pages in the new GDT. */
     for ( i = 0; i < nr_pages; i++ )
     {
         struct page_info *page;
-        pfns[i] = frames[i];
+
         page = get_page_from_gfn(d, frames[i], NULL, P2M_ALLOC);
         if ( !page )
             goto fail;
@@ -4476,7 +4471,6 @@ long set_gdt(struct vcpu *v,
         l1e_write(&pl1e[i], l1e_from_pfn(frames[i], __PAGE_HYPERVISOR_RW));
     }
 
-    xfree(pfns);
     return 0;
 
  fail:
@@ -4484,7 +4478,6 @@ long set_gdt(struct vcpu *v,
     {
         put_page_and_type(mfn_to_page(frames[i]));
     }
-    xfree(pfns);
     return -EINVAL;
 }