linux-kernel - [RFC v6 56/62] selftest/vm: detect no key violation on a freed key

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Message-Id: <1500177424-13695-57-git-send-email-linuxram@us.ibm.com>
Date:   Sat, 15 Jul 2017 20:56:58 -0700
From:   Ram Pai <linuxram@...ibm.com>
To:     linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        linux-arch@...r.kernel.org, linux-mm@...ck.org, x86@...nel.org,
        linux-doc@...r.kernel.org, linux-kselftest@...r.kernel.org
Cc:     benh@...nel.crashing.org, paulus@...ba.org, mpe@...erman.id.au,
        khandual@...ux.vnet.ibm.com, aneesh.kumar@...ux.vnet.ibm.com,
        bsingharora@...il.com, dave.hansen@...el.com, hbabu@...ibm.com,
        linuxram@...ibm.com, arnd@...db.de, akpm@...ux-foundation.org,
        corbet@....net, mingo@...hat.com, mhocko@...nel.org
Subject: [RFC v6 56/62] selftest/vm: detect no key violation on a freed key

a access-denied key should not trigger any key violation
after the key has been freed.

Signed-off-by: Ram Pai <linuxram@...ibm.com>
---
 tools/testing/selftests/vm/protection_keys.c |   25 +++++++++++++++++++++++++
 1 files changed, 25 insertions(+), 0 deletions(-)

diff --git a/tools/testing/selftests/vm/protection_keys.c b/tools/testing/selftests/vm/protection_keys.c
index bf27bcd..47c23cc 100644
--- a/tools/testing/selftests/vm/protection_keys.c
+++ b/tools/testing/selftests/vm/protection_keys.c
@@ -1026,6 +1026,30 @@ void test_read_of_access_disabled_region_with_page_already_mapped(int *ptr,
 	expected_pkey_fault(pkey);
 }
 
+void test_read_of_access_disabled_but_freed_key_region(int *ptr, u16 pkey)
+{
+	int ptr_contents;
+
+	dprintf1("disabling access to PKEY[%02d], doing read @ %p\n",
+			 pkey, ptr);
+
+	/* read the content */
+	ptr_contents = read_ptr(ptr);
+	do_not_expect_pkey_fault();
+
+	/* deny key access */
+	pkey_access_deny(pkey);
+	ptr_contents = read_ptr(ptr);
+	dprintf1("*ptr: %d\n", ptr_contents);
+	expected_pkey_fault(pkey);
+
+	/* free the key without restoring access */
+	pkey_access_deny(pkey);
+	sys_pkey_free(pkey);
+	ptr_contents = read_ptr(ptr);
+	do_not_expect_pkey_fault();
+}
+
 void test_write_of_write_disabled_region(int *ptr, u16 pkey)
 {
 	dprintf1("disabling write access to PKEY[%02d], doing write\n", pkey);
@@ -1333,6 +1357,7 @@ void test_mprotect_pkey_on_unsupported_cpu(int *ptr, u16 pkey)
 	test_pkey_syscalls_on_non_allocated_pkey,
 	test_pkey_syscalls_bad_args,
 	test_pkey_alloc_exhaust,
+	test_read_of_access_disabled_but_freed_key_region,
 };
 
 void run_tests_once(void)
-- 
1.7.1