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([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id t14sm10993993ejc.121.2021.05.03.07.05.21 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 03 May 2021 07:05:22 -0700 (PDT) Subject: Re: [PATCH][next] KVM: x86: Fix potential fput on a null source_kvm_file To: Colin King , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H . Peter Anvin" , Nathan Tempelman , kvm@vger.kernel.org Cc: kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org References: <20210430170303.131924-1-colin.king@canonical.com> From: Paolo Bonzini Message-ID: <9d28cde2-7aff-64bb-26f4-9909344676e5@redhat.com> Date: Mon, 3 May 2021 16:05:21 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: <20210430170303.131924-1-colin.king@canonical.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: kernel-janitors@vger.kernel.org On 30/04/21 19:03, Colin King wrote: > From: Colin Ian King > > 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 > --- > 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