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[91.219.240.2]) by smtp.gmail.com with ESMTPSA id dc24sm7251220ejb.201.2022.01.26.03.08.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 26 Jan 2022 03:08:56 -0800 (PST) From: Vitaly Kuznetsov To: Sean Christopherson , Paolo Bonzini Cc: Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, syzbot+be576ad7655690586eec@syzkaller.appspotmail.com Subject: Re: [PATCH] KVM: x86: Free kvm_cpuid_entry2 array on post-KVM_RUN KVM_SET_CPUID{,2} In-Reply-To: <20220125210445.2053429-1-seanjc@google.com> References: <20220125210445.2053429-1-seanjc@google.com> Date: Wed, 26 Jan 2022 12:08:55 +0100 Message-ID: <875yq6iwjc.fsf@redhat.com> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Sean Christopherson writes: > Free the "struct kvm_cpuid_entry2" array on successful post-KVM_RUN > KVM_SET_CPUID{,2} to fix a memory leak, the callers of kvm_set_cpuid() > free the array only on failure. > > BUG: memory leak > unreferenced object 0xffff88810963a800 (size 2048): > comm "syz-executor025", pid 3610, jiffies 4294944928 (age 8.080s) > hex dump (first 32 bytes): > 00 00 00 00 00 00 00 00 00 00 00 00 0d 00 00 00 ................ > 47 65 6e 75 6e 74 65 6c 69 6e 65 49 00 00 00 00 GenuntelineI.... > backtrace: > [] kmalloc_node include/linux/slab.h:604 [inline] > [] kvmalloc_node+0x3e/0x100 mm/util.c:580 > [] kvmalloc include/linux/slab.h:732 [inline] > [] vmemdup_user+0x22/0x100 mm/util.c:199 > [] kvm_vcpu_ioctl_set_cpuid2+0x8f/0xf0 arch/x86/kvm/cpuid.c:423 > [] kvm_arch_vcpu_ioctl+0xb99/0x1e60 arch/x86/kvm/x86.c:5251 > [] kvm_vcpu_ioctl+0x4ad/0x950 arch/x86/kvm/../../../virt/kvm/kvm_main.c:4066 > [] vfs_ioctl fs/ioctl.c:51 [inline] > [] __do_sys_ioctl fs/ioctl.c:874 [inline] > [] __se_sys_ioctl fs/ioctl.c:860 [inline] > [] __x64_sys_ioctl+0xfc/0x140 fs/ioctl.c:860 > [] do_syscall_x64 arch/x86/entry/common.c:50 [inline] > [] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 > [] entry_SYSCALL_64_after_hwframe+0x44/0xae > > Fixes: c6617c61e8fe ("KVM: x86: Partially allow KVM_SET_CPUID{,2} after KVM_RUN") > Cc: stable@vger.kernel.org > Reported-by: syzbot+be576ad7655690586eec@syzkaller.appspotmail.com > Signed-off-by: Sean Christopherson > --- > arch/x86/kvm/cpuid.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c > index 3902c28fb6cb..0a08db384fb9 100644 > --- a/arch/x86/kvm/cpuid.c > +++ b/arch/x86/kvm/cpuid.c > @@ -346,8 +346,14 @@ static int kvm_set_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid_entry2 *e2, > * KVM_SET_CPUID{,2} again. To support this legacy behavior, check > * whether the supplied CPUID data is equal to what's already set. > */ > - if (vcpu->arch.last_vmentry_cpu != -1) > - return kvm_cpuid_check_equal(vcpu, e2, nent); > + if (vcpu->arch.last_vmentry_cpu != -1) { > + r = kvm_cpuid_check_equal(vcpu, e2, nent); > + if (r) > + return r; > + > + kvfree(e2); > + return 0; > + } > > r = kvm_check_cpuid(vcpu, e2, nent); > if (r) > > base-commit: e2e83a73d7ce66f62c7830a85619542ef59c90e4 Reviewed-by: Vitaly Kuznetsov Thanks! -- Vitaly