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Peter Anvin" Cc: kai.huang@intel.com, reinette.chatre@intel.com, kristen@linux.intel.com, seanjc@google.com, stable@vger.kernel.org Subject: [PATCH] x86/sgx: fix a NULL pointer Date: Mon, 17 Jul 2023 11:17:32 -0700 Message-Id: <20230717181732.84039-1-haitao.huang@linux.intel.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 X-Spam-Status: No, score=-2.0 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_EF,RCVD_IN_DNSWL_BLOCKED, RCVD_IN_MSPIKE_H3,RCVD_IN_MSPIKE_WL,SPF_HELO_NONE,SPF_NONE, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1771692959545426999 X-GMAIL-MSGID: 1771692959545426999 Under heavy load, the SGX EPC reclaimers (current ksgxd or future EPC cgroup worker) may reclaim the SECS EPC page for an enclave and set encl->secs.epc_page to NULL. But the SECS EPC page is used for EAUG in the SGX #PF handler without checking for NULL and reloading. Fix this by checking if SECS is loaded before EAUG and load it if it was reclaimed. Fixes: 5a90d2c3f5ef8 ("x86/sgx: Support adding of pages to an initialized enclave") Cc: stable@vger.kernel.org Signed-off-by: Haitao Huang --- arch/x86/kernel/cpu/sgx/encl.c | 25 ++++++++++++++++++++----- arch/x86/kernel/cpu/sgx/main.c | 4 ++++ 2 files changed, 24 insertions(+), 5 deletions(-) diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c index 2a0e90fe2abc..d39e502bb7b0 100644 --- a/arch/x86/kernel/cpu/sgx/encl.c +++ b/arch/x86/kernel/cpu/sgx/encl.c @@ -235,6 +235,16 @@ static struct sgx_epc_page *sgx_encl_eldu(struct sgx_encl_page *encl_page, return epc_page; } +static struct sgx_epc_page *sgx_encl_load_secs(struct sgx_encl *encl) +{ + struct sgx_epc_page *epc_page = encl->secs.epc_page; + + if (!epc_page) { + epc_page = sgx_encl_eldu(&encl->secs, NULL); + } + return epc_page; +} + static struct sgx_encl_page *__sgx_encl_load_page(struct sgx_encl *encl, struct sgx_encl_page *entry) { @@ -248,11 +258,9 @@ static struct sgx_encl_page *__sgx_encl_load_page(struct sgx_encl *encl, return entry; } - if (!(encl->secs.epc_page)) { - epc_page = sgx_encl_eldu(&encl->secs, NULL); - if (IS_ERR(epc_page)) - return ERR_CAST(epc_page); - } + epc_page = sgx_encl_load_secs(encl); + if (IS_ERR(epc_page)) + return ERR_CAST(epc_page); epc_page = sgx_encl_eldu(entry, encl->secs.epc_page); if (IS_ERR(epc_page)) @@ -339,6 +347,13 @@ static vm_fault_t sgx_encl_eaug_page(struct vm_area_struct *vma, mutex_lock(&encl->lock); + epc_page = sgx_encl_load_secs(encl); + if (IS_ERR(epc_page)) { + if (PTR_ERR(epc_page) == -EBUSY) + vmret = VM_FAULT_NOPAGE; + goto err_out_unlock; + } + epc_page = sgx_alloc_epc_page(encl_page, false); if (IS_ERR(epc_page)) { if (PTR_ERR(epc_page) == -EBUSY) diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c index 166692f2d501..4662a364ce62 100644 --- a/arch/x86/kernel/cpu/sgx/main.c +++ b/arch/x86/kernel/cpu/sgx/main.c @@ -257,6 +257,10 @@ static void sgx_reclaimer_write(struct sgx_epc_page *epc_page, mutex_lock(&encl->lock); + /* Should not be possible */ + if (WARN_ON(!(encl->secs.epc_page))) + goto out; + sgx_encl_ewb(epc_page, backing); encl_page->epc_page = NULL; encl->secs_child_cnt--;