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Subject[PATCH] kvm: fix incorrect NULL check on list iterator
Date
The bug is here:
if (!p)
return ret;

The list iterator value 'p' will *always* be set and non-NULL by
list_for_each_entry(), so it is incorrect to assume that the iterator
value will be NULL if the list is empty or no element is found.

To fix the bug, Use a new value 'iter' as the list iterator, while use
the old value 'p' as a dedicated variable to point to the found element.

Cc: stable@vger.kernel.org
Fixes: dfaa973ae9605 ("KVM: PPC: Book3S HV: In H_SVM_INIT_DONE, migrate remaining normal-GFNs to secure-GFNs")
Signed-off-by: Xiaomeng Tong <xiam0nd.tong@gmail.com>
---
arch/powerpc/kvm/book3s_hv_uvmem.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_hv_uvmem.c b/arch/powerpc/kvm/book3s_hv_uvmem.c
index e414ca44839f..0cb20ee6a632 100644
--- a/arch/powerpc/kvm/book3s_hv_uvmem.c
+++ b/arch/powerpc/kvm/book3s_hv_uvmem.c
@@ -360,13 +360,15 @@ static bool kvmppc_gfn_is_uvmem_pfn(unsigned long gfn, struct kvm *kvm,
static bool kvmppc_next_nontransitioned_gfn(const struct kvm_memory_slot *memslot,
struct kvm *kvm, unsigned long *gfn)
{
- struct kvmppc_uvmem_slot *p;
+ struct kvmppc_uvmem_slot *p = NULL, *iter;
bool ret = false;
unsigned long i;

- list_for_each_entry(p, &kvm->arch.uvmem_pfns, list)
- if (*gfn >= p->base_pfn && *gfn < p->base_pfn + p->nr_pfns)
+ list_for_each_entry(iter, &kvm->arch.uvmem_pfns, list)
+ if (*gfn >= iter->base_pfn && *gfn < iter->base_pfn + iter->nr_pfns) {
+ p = iter;
break;
+ }
if (!p)
return ret;
/*
--
2.17.1
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