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Fri, 25 Mar 2022 08:51:44 -0700 (PDT) Received: from [192.168.1.11] ([94.103.225.225]) by smtp.gmail.com with ESMTPSA id o7-20020ac24c47000000b0044a15c4e0aesm741758lfk.272.2022.03.25.08.51.42 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 25 Mar 2022 08:51:43 -0700 (PDT) Content-Type: multipart/mixed; boundary="------------xd9s8aJo1C2Exy5fYVGAfcXa" Message-ID: <1a1172db-12f6-1173-b526-89e4da00e96a@gmail.com> Date: Fri, 25 Mar 2022 18:51:40 +0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.6.1 Subject: Re: [syzbot] general protection fault in kvm_mmu_uninit_tdp_mmu Content-Language: en-US To: syzbot , bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, jmattson@google.com, joro@8bytes.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, mingo@redhat.com, pbonzini@redhat.com, seanjc@google.com, syzkaller-bugs@googlegroups.com, tglx@linutronix.de, vkuznets@redhat.com, wanpengli@tencent.com, x86@kernel.org References: <000000000000a5cb1305db0aaf48@google.com> From: Pavel Skripkin In-Reply-To: <000000000000a5cb1305db0aaf48@google.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is a multi-part message in MIME format. --------------xd9s8aJo1C2Exy5fYVGAfcXa Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 3/25/22 16:10, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: f9006d9269ea Add linux-next specific files for 20220321 > git tree: linux-next > console output: https://syzkaller.appspot.com/x/log.txt?x=101191bd700000 > kernel config: https://syzkaller.appspot.com/x/.config?x=c1619ffa2b0259a1 > dashboard link: https://syzkaller.appspot.com/bug?extid=717ed82268812a643b28 > compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=109e8f5d700000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1666180b700000 > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+717ed82268812a643b28@syzkaller.appspotmail.com > The following code is not safe: arch/x86/kvm/mmu/tdp_mmu.c: 28 kvm->arch.tdp_mmu_zap_wq = 29 alloc_workqueue("kvm", WQ_UNBOUND|WQ_MEM_RECLAIM|WQ_CPU_INTENSIVE, 0); 30 31 return true; Looks like kvm_mmu_init_tdp_mmu() error value is just ignored, and then all kvm_*_init_vm() functions are void, so the easiest solution is to check that tdp_mmu_zap_wq is valid pointer #syz test: git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master With regards, Pavel Skripkin --------------xd9s8aJo1C2Exy5fYVGAfcXa Content-Type: text/plain; charset=UTF-8; name="ph" Content-Disposition: attachment; filename="ph" Content-Transfer-Encoding: base64 ZGlmZiAtLWdpdCBhL2FyY2gveDg2L2t2bS9tbXUvdGRwX21tdS5jIGIvYXJjaC94ODYva3Zt L21tdS90ZHBfbW11LmMKaW5kZXggZTdlNzg3NjI1MWIzLi5iM2U4ZmY3YWM1YjAgMTAwNjQ0 Ci0tLSBhL2FyY2gveDg2L2t2bS9tbXUvdGRwX21tdS5jCisrKyBiL2FyY2gveDg2L2t2bS9t bXUvdGRwX21tdS5jCkBAIC00OCw4ICs0OCwxMCBAQCB2b2lkIGt2bV9tbXVfdW5pbml0X3Rk cF9tbXUoc3RydWN0IGt2bSAqa3ZtKQogCWlmICgha3ZtLT5hcmNoLnRkcF9tbXVfZW5hYmxl ZCkKIAkJcmV0dXJuOwogCi0JZmx1c2hfd29ya3F1ZXVlKGt2bS0+YXJjaC50ZHBfbW11X3ph cF93cSk7Ci0JZGVzdHJveV93b3JrcXVldWUoa3ZtLT5hcmNoLnRkcF9tbXVfemFwX3dxKTsK KwlpZiAoa3ZtLT5hcmNoLnRkcF9tbXVfemFwX3dxKSB7CisJCWZsdXNoX3dvcmtxdWV1ZShr dm0tPmFyY2gudGRwX21tdV96YXBfd3EpOworCQlkZXN0cm95X3dvcmtxdWV1ZShrdm0tPmFy Y2gudGRwX21tdV96YXBfd3EpOworCX0KIAogCVdBUk5fT04oIWxpc3RfZW1wdHkoJmt2bS0+ YXJjaC50ZHBfbW11X3BhZ2VzKSk7CiAJV0FSTl9PTighbGlzdF9lbXB0eSgma3ZtLT5hcmNo LnRkcF9tbXVfcm9vdHMpKTsKQEAgLTExOSw5ICsxMjEsMTEgQEAgc3RhdGljIHZvaWQgdGRw X21tdV96YXBfcm9vdF93b3JrKHN0cnVjdCB3b3JrX3N0cnVjdCAqd29yaykKIAogc3RhdGlj IHZvaWQgdGRwX21tdV9zY2hlZHVsZV96YXBfcm9vdChzdHJ1Y3Qga3ZtICprdm0sIHN0cnVj dCBrdm1fbW11X3BhZ2UgKnJvb3QpCiB7Ci0Jcm9vdC0+dGRwX21tdV9hc3luY19kYXRhID0g a3ZtOwotCUlOSVRfV09SSygmcm9vdC0+dGRwX21tdV9hc3luY193b3JrLCB0ZHBfbW11X3ph cF9yb290X3dvcmspOwotCXF1ZXVlX3dvcmsoa3ZtLT5hcmNoLnRkcF9tbXVfemFwX3dxLCAm cm9vdC0+dGRwX21tdV9hc3luY193b3JrKTsKKwlpZiAoa3ZtLT5hcmNoLnRkcF9tbXVfemFw X3dxKSB7CisJCXJvb3QtPnRkcF9tbXVfYXN5bmNfZGF0YSA9IGt2bTsKKwkJSU5JVF9XT1JL KCZyb290LT50ZHBfbW11X2FzeW5jX3dvcmssIHRkcF9tbXVfemFwX3Jvb3Rfd29yayk7CisJ CXF1ZXVlX3dvcmsoa3ZtLT5hcmNoLnRkcF9tbXVfemFwX3dxLCAmcm9vdC0+dGRwX21tdV9h c3luY193b3JrKTsKKwl9CiB9CiAKIHN0YXRpYyBpbmxpbmUgYm9vbCBrdm1fdGRwX3Jvb3Rf bWFya19pbnZhbGlkKHN0cnVjdCBrdm1fbW11X3BhZ2UgKnBhZ2UpCg== --------------xd9s8aJo1C2Exy5fYVGAfcXa--