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From 9f6f35b833d295acaaa2d8ff8cf309bf688cfd50 Mon Sep 17 00:00:00 2001
From: Wei Liu <wei.liu2@citrix.com>
Date: Sat, 11 Jan 2020 21:57:42 +0000
Subject: [PATCH 2/3] x86/mm: Refactor modify_xen_mappings to have one exit
path
We will soon need to perform clean-ups before returning.
No functional change.
This is part of XSA-345.
Reported-by: Hongyan Xia <hongyxia@amazon.com>
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: Hongyan Xia <hongyxia@amazon.com>
Signed-off-by: George Dunlap <george.dunlap@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
---
xen/arch/x86/mm.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index 133a393875..af726d3274 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -5570,6 +5570,7 @@ int modify_xen_mappings(unsigned long s, unsigned long e, unsigned int nf)
l1_pgentry_t *pl1e;
unsigned int i;
unsigned long v = s;
+ int rc = -ENOMEM;
/* Set of valid PTE bits which may be altered. */
#define FLAGS_MASK (_PAGE_NX|_PAGE_RW|_PAGE_PRESENT)
@@ -5611,7 +5612,8 @@ int modify_xen_mappings(unsigned long s, unsigned long e, unsigned int nf)
/* PAGE1GB: shatter the superpage and fall through. */
pl2e = alloc_xen_pagetable();
if ( !pl2e )
- return -ENOMEM;
+ goto out;
+
for ( i = 0; i < L2_PAGETABLE_ENTRIES; i++ )
l2e_write(pl2e + i,
l2e_from_pfn(l3e_get_pfn(*pl3e) +
@@ -5666,7 +5668,8 @@ int modify_xen_mappings(unsigned long s, unsigned long e, unsigned int nf)
/* PSE: shatter the superpage and try again. */
pl1e = alloc_xen_pagetable();
if ( !pl1e )
- return -ENOMEM;
+ goto out;
+
for ( i = 0; i < L1_PAGETABLE_ENTRIES; i++ )
l1e_write(&pl1e[i],
l1e_from_pfn(l2e_get_pfn(*pl2e) + i,
@@ -5795,7 +5798,10 @@ int modify_xen_mappings(unsigned long s, unsigned long e, unsigned int nf)
flush_area(NULL, FLUSH_TLB_GLOBAL);
#undef FLAGS_MASK
- return 0;
+ rc = 0;
+
+ out:
+ return rc;
}
#undef flush_area
--
2.25.1
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