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AHgh+RpIRrhBPIGhEAa7L2+7F6rrkGgimTqcvn1gdbTitUOW6+tMDdkBn6A+rb3MxcrzgVJeNqXtOI84uUsejX8=@vger.kernel.org X-Gm-Message-State: AOJu0Yy5z2iVs2xKC4Vuagppy8UaH07fb3VbMuhFAiIvVQpbS9OVIdFK yjs35GDi4v8G4MB/Ij517C5Pk9ZMY+5J0xA/2NpzhzSRTMwOiT8mBeJ6myvWIu6bQ3XiZ3TnZ2P OpZLp4g== X-Received: from pgjx8.prod.google.com ([2002:a63:fe48:0:b0:c9a:ddfd:b879]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a20:9595:b0:3c4:36ef:3dc9 with SMTP id adf61e73a8af0-3cb85e45aa3mr29843874637.17.1786111898994; Fri, 07 Aug 2026 07:11:38 -0700 (PDT) Date: Fri, 7 Aug 2026 07:11:38 -0700 In-Reply-To: <20260807071934.786879-1-zeng_chi911@163.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260807071934.786879-1-zeng_chi911@163.com> Message-ID: Subject: Re: [PATCH] KVM: Remove the kvm debugfs directory if kvm_init() fails From: Sean Christopherson To: Zeng Chi Cc: pbonzini@redhat.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, zengchi@kylinos.cn, stable@vger.kernel.org Content-Type: text/plain; charset="us-ascii" On Fri, Aug 07, 2026, Zeng Chi wrote: > From: zengchi > > kvm_init_debug() creates the "kvm" debugfs directory along with all of > the VM/vCPU stat files, but none of kvm_init()'s error paths removes it. > If kvm_vfio_ops_init(), kvm_gmem_init(), kvm_init_virtualization() or > misc_register() fails, the directory is leaked, and none of kvm_init()'s > callers invokes kvm_exit() on failure, i.e. nothing papers over the > leak. > > The stale /sys/kernel/debug/kvm directory isn't just cosmetic: a > subsequent attempt to load KVM makes debugfs_create_dir() fail with > -EEXIST, after which kvm_debugfs_dir holds an ERR_PTR and all stat > files are silently never created again. Worse, the leaked stat files > reference file_operations and stat data that live in the KVM module; if > the module is unloaded after the failed initialization, reading the > stale files is a use-after-free. > > Remove the debugfs directory in the error path, mirroring kvm_exit(). > > Fixes: 2b0128127373 ("KVM: Register /dev/kvm as the _very_ last thing during initialization") > Cc: stable@vger.kernel.org > Signed-off-by: zengchi > --- > virt/kvm/kvm_main.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index 45e784462ec6..8a503ac1adbd 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -6553,6 +6553,7 @@ int kvm_init(unsigned vcpu_size, unsigned vcpu_align, struct module *module) > err_gmem: > kvm_vfio_ops_exit(); > err_vfio: > + debugfs_remove_recursive(kvm_debugfs_dir); > kvm_async_pf_deinit(); > err_async_pf: > kvm_irqfd_exit(); > -- Already posted (twice) and applied: https://lore.kernel.org/all/20260706095910.39798-1-leixiang@kylinos.cn