linux-kernel - [RFC v6 58/62] selftest/vm: detect no write key-violation on a freed key

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Message-Id: <1500177424-13695-59-git-send-email-linuxram@us.ibm.com>
Date:   Sat, 15 Jul 2017 20:57:00 -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 58/62] selftest/vm: detect no write key-violation on a freed key

a write-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 |   18 ++++++++++++++++++
 1 files changed, 18 insertions(+), 0 deletions(-)

diff --git a/tools/testing/selftests/vm/protection_keys.c b/tools/testing/selftests/vm/protection_keys.c
index e35cef5..07df8cf 100644
--- a/tools/testing/selftests/vm/protection_keys.c
+++ b/tools/testing/selftests/vm/protection_keys.c
@@ -1068,6 +1068,23 @@ void test_write_of_write_disabled_region(int *ptr, u16 pkey)
 	*ptr = __LINE__;
 	expected_pkey_fault(pkey);
 }
+
+void test_write_of_write_disabled_but_freed_key_region(int *ptr, u16 pkey)
+{
+	dprintf1("disabling write access to PKEY[%02d], doing write\n", pkey);
+	*ptr = __LINE__;
+	do_not_expect_pkey_fault();
+
+	pkey_write_deny(pkey);
+	*ptr = __LINE__;
+	expected_pkey_fault(pkey);
+
+	pkey_write_deny(pkey);
+	sys_pkey_free(pkey);
+	*ptr = __LINE__;
+	do_not_expect_pkey_fault();
+}
+
 void test_write_of_access_disabled_region(int *ptr, u16 pkey)
 {
 	dprintf1("disabling access to PKEY[%02d], doing write\n", pkey);
@@ -1370,6 +1387,7 @@ void test_mprotect_pkey_on_unsupported_cpu(int *ptr, u16 pkey)
 	test_pkey_syscalls_bad_args,
 	test_pkey_alloc_exhaust,
 	test_read_of_access_disabled_but_freed_key_region,
+	test_write_of_write_disabled_but_freed_key_region,
 };
 
 void run_tests_once(void)
-- 
1.7.1