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From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc: linux-sgx@vger.kernel.org
Subject: [PATCH for_v23 v2 3/9] x86/sgx: Fix a memory leak in sgx_encl_destroy()
Date: Thu, 10 Oct 2019 16:21:02 -0700
Message-ID: <20191010232108.27075-4-sean.j.christopherson@intel.com> (raw)
In-Reply-To: <20191010232108.27075-1-sean.j.christopherson@intel.com>

Delete an enclave page's entry in the radix tree regardless of whether
or not it has an associated EPC page, and free the page itself when it's
deleted from the radix tree.

Don't free/delete anything if the page is held by the reclaimer, as the
reclaimer needs the page itself and the driver needs the radix entry to
re-process the entry during sgx_encl_release().

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 arch/x86/kernel/cpu/sgx/encl.c | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c
index ea21d3737a32..c1d2df186b2d 100644
--- a/arch/x86/kernel/cpu/sgx/encl.c
+++ b/arch/x86/kernel/cpu/sgx/encl.c
@@ -469,14 +469,19 @@ void sgx_encl_destroy(struct sgx_encl *encl)
 	radix_tree_for_each_slot(slot, &encl->page_tree, &iter, 0) {
 		entry = *slot;
 		if (entry->epc_page) {
-			if (!sgx_free_page(entry->epc_page)) {
-				encl->secs_child_cnt--;
-				entry->epc_page = NULL;
-			}
-
-			radix_tree_delete(&entry->encl->page_tree,
-					  PFN_DOWN(entry->desc));
+			/*
+			 * The page and its radix tree entry cannot be freed
+			 * if the page is being held by the reclaimer.
+			 */
+			if (sgx_free_page(entry->epc_page))
+				continue;
+			encl->secs_child_cnt--;
+			entry->epc_page = NULL;
 		}
+
+		radix_tree_delete(&entry->encl->page_tree,
+				  PFN_DOWN(entry->desc));
+		kfree(entry);
 	}
 
 	if (!encl->secs_child_cnt && encl->secs.epc_page) {
-- 
2.22.0


  parent reply index

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-10 23:20 [PATCH for_v23 v2 0/9] x86/sgx: Misc page related fixes Sean Christopherson
2019-10-10 23:21 ` [PATCH for_v23 v2 1/9] x86/sgx: WARN once if an enclave is released with unfreed EPC pages Sean Christopherson
2019-10-10 23:21 ` [PATCH for_v23 v2 2/9] x86/sgx: Do not EWB SECS if the enclave is dead Sean Christopherson
2019-10-10 23:21 ` Sean Christopherson [this message]
2019-10-10 23:21 ` [PATCH for_v23 v2 4/9] x86/sgx: WARN on any non-zero return from __eremove() Sean Christopherson
2019-10-10 23:21 ` [PATCH for_v23 v2 5/9] x86/sgx: WARN only once if EREMOVE fails Sean Christopherson
2019-10-10 23:21 ` [PATCH for_v23 v2 6/9] x86/sgx: Split second half of sgx_free_page() to a separate helper Sean Christopherson
2019-10-10 23:21 ` [PATCH for_v23 v2 7/9] x86/sgx: Use the post-reclaim variant of __sgx_free_page() Sean Christopherson
2019-10-10 23:21 ` [PATCH for_v23 v2 8/9] x86/sgx: Don't update free page count if EPC section allocation fails Sean Christopherson
2019-10-10 23:21 ` [PATCH for_v23 v2 9/9] x86/sgx: Reinstate per EPC section free page counts Sean Christopherson

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