* [PATCH -next] KVM: arm64: Fix possible null-ptr-deref in idregs_debug_show
@ 2024-10-24 8:33 Gaosheng Cui
2024-10-24 9:29 ` Marc Zyngier
0 siblings, 1 reply; 3+ messages in thread
From: Gaosheng Cui @ 2024-10-24 8:33 UTC (permalink / raw)
To: maz, oliver.upton, joey.gouly, suzuki.poulose, yuzenghui,
catalin.marinas, will, sebott, cuigaosheng1, wangweiyang2
Cc: linux-arm-kernel, kvmarm
The idregs_debug_show() maybe return nullptr, we need to check desc
before dereference it to avoid possible null pointer dereferences.
Fixes: 410db103f6eb ("KVM: arm64: Make idregs debugfs iterator search sysreg table directly")
Signed-off-by: Gaosheng Cui <cuigaosheng1@huawei.com>
---
arch/arm64/kvm/sys_regs.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index ff8c4e1b847e..b1c59773b9c0 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -4135,7 +4135,7 @@ static int idregs_debug_show(struct seq_file *s, void *v)
desc = idregs_debug_find(kvm, kvm->arch.idreg_debugfs_iter);
- if (!desc->name)
+ if (!desc || !desc->name)
return 0;
seq_printf(s, "%20s:\t%016llx\n",
--
2.25.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH -next] KVM: arm64: Fix possible null-ptr-deref in idregs_debug_show
2024-10-24 8:33 [PATCH -next] KVM: arm64: Fix possible null-ptr-deref in idregs_debug_show Gaosheng Cui
@ 2024-10-24 9:29 ` Marc Zyngier
2024-10-29 3:58 ` cuigaosheng
0 siblings, 1 reply; 3+ messages in thread
From: Marc Zyngier @ 2024-10-24 9:29 UTC (permalink / raw)
To: Gaosheng Cui
Cc: oliver.upton, joey.gouly, suzuki.poulose, yuzenghui,
catalin.marinas, will, sebott, wangweiyang2, linux-arm-kernel,
kvmarm
On Thu, 24 Oct 2024 09:33:50 +0100,
Gaosheng Cui <cuigaosheng1@huawei.com> wrote:
>
> The idregs_debug_show() maybe return nullptr, we need to check desc
> before dereference it to avoid possible null pointer dereferences.
>
> Fixes: 410db103f6eb ("KVM: arm64: Make idregs debugfs iterator search sysreg table directly")
> Signed-off-by: Gaosheng Cui <cuigaosheng1@huawei.com>
> ---
> arch/arm64/kvm/sys_regs.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index ff8c4e1b847e..b1c59773b9c0 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -4135,7 +4135,7 @@ static int idregs_debug_show(struct seq_file *s, void *v)
>
> desc = idregs_debug_find(kvm, kvm->arch.idreg_debugfs_iter);
>
> - if (!desc->name)
> + if (!desc || !desc->name)
> return 0;
>
> seq_printf(s, "%20s:\t%016llx\n",
Can you show a case where this happens in practice?
The check for NULL is already in idregs_debug_next(), and I don't see
how this can actually be triggered.
Thanks,
M.
--
Without deviation from the norm, progress is not possible.
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH -next] KVM: arm64: Fix possible null-ptr-deref in idregs_debug_show
2024-10-24 9:29 ` Marc Zyngier
@ 2024-10-29 3:58 ` cuigaosheng
0 siblings, 0 replies; 3+ messages in thread
From: cuigaosheng @ 2024-10-29 3:58 UTC (permalink / raw)
To: Marc Zyngier
Cc: oliver.upton, joey.gouly, suzuki.poulose, yuzenghui,
catalin.marinas, will, sebott, wangweiyang2, linux-arm-kernel,
kvmarm
On 2024/10/24 17:29, Marc Zyngier wrote:
> On Thu, 24 Oct 2024 09:33:50 +0100,
> Gaosheng Cui <cuigaosheng1@huawei.com> wrote:
>> The idregs_debug_show() maybe return nullptr, we need to check desc
>> before dereference it to avoid possible null pointer dereferences.
>>
>> Fixes: 410db103f6eb ("KVM: arm64: Make idregs debugfs iterator search sysreg table directly")
>> Signed-off-by: Gaosheng Cui <cuigaosheng1@huawei.com>
>> ---
>> arch/arm64/kvm/sys_regs.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
>> index ff8c4e1b847e..b1c59773b9c0 100644
>> --- a/arch/arm64/kvm/sys_regs.c
>> +++ b/arch/arm64/kvm/sys_regs.c
>> @@ -4135,7 +4135,7 @@ static int idregs_debug_show(struct seq_file *s, void *v)
>>
>> desc = idregs_debug_find(kvm, kvm->arch.idreg_debugfs_iter);
>>
>> - if (!desc->name)
>> + if (!desc || !desc->name)
>> return 0;
>>
>> seq_printf(s, "%20s:\t%016llx\n",
> Can you show a case where this happens in practice?
>
> The check for NULL is already in idregs_debug_next(), and I don't see
> how this can actually be triggered.
I haven't found a scenario that can trigger this problem，this patch was
discovered during code review，I will try to prove it.
Thanks for your work.
>
> Thanks,
>
> M.
>
^ permalink raw reply [flat|nested] 3+ messages in thread
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2024-10-24 8:33 [PATCH -next] KVM: arm64: Fix possible null-ptr-deref in idregs_debug_show Gaosheng Cui
2024-10-24 9:29 ` Marc Zyngier
2024-10-29 3:58 ` cuigaosheng
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