2021-04-30 17:07:37

by Colin King

Subject: [PATCH][next] KVM: x86: Fix potential fput on a null source_kvm_file

From: Colin Ian King <[email protected]>

The fget can potentially return null, so the fput on the error return
path can cause a null pointer dereference. Fix this by checking for
a null source_kvm_file before doing a fput.

Addresses-Coverity: ("Dereference null return")
Fixes: 54526d1fd593 ("KVM: x86: Support KVM VMs sharing SEV context")
Signed-off-by: Colin Ian King <[email protected]>
---
arch/x86/kvm/svm/sev.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 1356ee095cd5..8b11c711a0e4 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -1764,7 +1764,8 @@ int svm_vm_copy_asid_from(struct kvm *kvm, unsigned int source_fd)
e_source_unlock:
mutex_unlock(&source_kvm->lock);
e_source_put:
- fput(source_kvm_file);
+ if (source_kvm_file)
+ fput(source_kvm_file);
return ret;
}

--
2.30.2

2021-05-03 18:08:53

by Paolo Bonzini

Subject: Re: [PATCH][next] KVM: x86: Fix potential fput on a null source_kvm_file

On 30/04/21 19:03, Colin King wrote:
> From: Colin Ian King <[email protected]>
>
> The fget can potentially return null, so the fput on the error return
> path can cause a null pointer dereference. Fix this by checking for
> a null source_kvm_file before doing a fput.
>
> Addresses-Coverity: ("Dereference null return")
> Fixes: 54526d1fd593 ("KVM: x86: Support KVM VMs sharing SEV context")
> Signed-off-by: Colin Ian King <[email protected]>
> ---
> arch/x86/kvm/svm/sev.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
> index 1356ee095cd5..8b11c711a0e4 100644
> --- a/arch/x86/kvm/svm/sev.c
> +++ b/arch/x86/kvm/svm/sev.c
> @@ -1764,7 +1764,8 @@ int svm_vm_copy_asid_from(struct kvm *kvm, unsigned int source_fd)
> e_source_unlock:
> mutex_unlock(&source_kvm->lock);
> e_source_put:
> - fput(source_kvm_file);
> + if (source_kvm_file)
> + fput(source_kvm_file);
> return ret;
> }
>
>

Queued, thanks.

Paolo