* [RESEND][PATCH] KVM: PPC: Book3S HV: fix incorrect NULL check on list iterator
@ 2022-04-14 6:21 Xiaomeng Tong
2022-05-24 10:51 ` Michael Ellerman
0 siblings, 1 reply; 2+ messages in thread
From: Xiaomeng Tong @ 2022-04-14 6:21 UTC (permalink / raw)
To: mpe, benh, paulus, akpm, liam.howlett, david, maz,
Felix.Kuehling, maciej.szmigiero, apopple, bharata, linuxram
Cc: linuxppc-dev, linux-kernel, Xiaomeng Tong, stable
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
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [RESEND][PATCH] KVM: PPC: Book3S HV: fix incorrect NULL check on list iterator
2022-04-14 6:21 [RESEND][PATCH] KVM: PPC: Book3S HV: fix incorrect NULL check on list iterator Xiaomeng Tong
@ 2022-05-24 10:51 ` Michael Ellerman
0 siblings, 0 replies; 2+ messages in thread
From: Michael Ellerman @ 2022-05-24 10:51 UTC (permalink / raw)
To: akpm, bharata, linuxram, Felix.Kuehling, mpe, paulus, benh,
maciej.szmigiero, maz, david, Xiaomeng Tong, liam.howlett,
apopple
Cc: linux-kernel, stable, linuxppc-dev
On Thu, 14 Apr 2022 14:21:03 +0800, Xiaomeng Tong wrote:
> 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.
>
> [...]
Applied to powerpc/topic/ppc-kvm.
[1/1] KVM: PPC: Book3S HV: fix incorrect NULL check on list iterator
https://git.kernel.org/powerpc/c/300981abddcb13f8f06ad58f52358b53a8096775
cheers
^ permalink raw reply [flat|nested] 2+ messages in thread
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