On 03/08/21 15:55, Ovidiu Panait wrote:
From: Sean Christopherson <seanjc@xxxxxxxxxx>
commit a9545779ee9e9e103648f6f2552e73cfe808d0f4 upstream
Use kvm_pfn_t, a.k.a. u64, for the local 'pfn' variable when retrieving
a so called "remapped" hva/pfn pair. In theory, the hva could resolve to
a pfn in high memory on a 32-bit kernel.
This bug was inadvertantly exposed by commit bd2fae8da794 ("KVM: do not
assume PTE is writable after follow_pfn"), which added an error PFN value
to the mix, causing gcc to comlain about overflowing the unsigned long.
arch/x86/kvm/../../../virt/kvm/kvm_main.c: In function ‘hva_to_pfn_remapped’:
include/linux/kvm_host.h:89:30: error: conversion from ‘long long unsigned int’
to ‘long unsigned int’ changes value from
‘9218868437227405314’ to ‘2’ [-Werror=overflow]
89 | #define KVM_PFN_ERR_RO_FAULT (KVM_PFN_ERR_MASK + 2)
| ^
virt/kvm/kvm_main.c:1935:9: note: in expansion of macro ‘KVM_PFN_ERR_RO_FAULT’
Cc: stable@xxxxxxxxxxxxxxx
Fixes: add6a0cd1c5b ("KVM: MMU: try to fix up page faults before giving up")
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Message-Id: <20210208201940.1258328-1-seanjc@xxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Ovidiu Panait <ovidiu.panait@xxxxxxxxxxxxx>
---
virt/kvm/kvm_main.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 469361d01116..36b9f2b29071 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1497,7 +1497,7 @@ static int hva_to_pfn_remapped(struct vm_area_struct *vma,
bool write_fault, bool *writable,
kvm_pfn_t *p_pfn)
{
- unsigned long pfn;
+ kvm_pfn_t pfn;
pte_t *ptep;
spinlock_t *ptl;
int r;
Acked-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
