Patch "x86/pkeys/selftests: Add a test for pkey 0" has been added to the 4.14-stable tree

This is a note to let you know that I've just added the patch titled

x86/pkeys/selftests: Add a test for pkey 0

to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:

     x86-pkeys-selftests-add-a-test-for-pkey-0.patch

and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Dave Hansen <[email protected]>
Date: Wed, 9 May 2018 10:13:56 -0700
Subject: x86/pkeys/selftests: Add a test for pkey 0

From: Dave Hansen <[email protected]>

[ Upstream commit 3488a600d90bcaf061b104dbcfbdc8d99b398312 ]

Protection key 0 is the default key for all memory and will not normally come back from pkey_alloc(). But, you might still want pass it to mprotect_pkey().

This check ensures that you can use pkey 0.

---
 tools/testing/selftests/x86/protection_keys.c |   30 ++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

@@ -1184,6 +1184,35 @@ void test_pkey_alloc_exhaust(int *ptr, u
 	}
 }
 
+/*
+ * pkey 0 is special.  It is allocated by default, so you do not
+ * have to call pkey_alloc() to use it first.  Make sure that it
+ * is usable.
+ */
+void test_mprotect_with_pkey_0(int *ptr, u16 pkey)
+{
+	long size;
+	int prot;
+
+	assert(pkey_last_malloc_record);
+	size = pkey_last_malloc_record->size;
+	/*
+	 * This is a bit of a hack.  But mprotect() requires
+	 * huge-page-aligned sizes when operating on hugetlbfs.
+	 * So, make sure that we use something that's a multiple
+	 * of a huge page when we can.
+	 */
+	if (size >= HPAGE_SIZE)
+		size = HPAGE_SIZE;
+	prot = pkey_last_malloc_record->prot;
+
+	/* Use pkey 0 */
+	mprotect_pkey(ptr, size, prot, 0);
+
+	/* Make sure that we can set it back to the original pkey. */
+	mprotect_pkey(ptr, size, prot, pkey);
+}
+
 void test_ptrace_of_child(int *ptr, u16 pkey)
 {
 	__attribute__((__unused__)) int peek_result;

@@ -1378,6 +1407,7 @@ void (*pkey_tests[])(int *ptr, u16 pkey)
 	test_kernel_gup_write_to_write_disabled_region,
 	test_executing_on_unreadable_memory,
 	test_implicit_mprotect_exec_only_memory,
+	test_mprotect_with_pkey_0,
 	test_ptrace_of_child,
 	test_pkey_syscalls_on_non_allocated_pkey,
 	test_pkey_syscalls_bad_args,

Patches currently in stable-queue which might be from [email protected] are

queue-4.14/x86-pkeys-selftests-factor-out-instruction-page.patch queue-4.14/x86-pkeys-selftests-fix-pointer-math.patch queue-4.14/x86-pkeys-selftests-adjust-the-self-test-to-fresh-distros-that-export-the-pkeys-abi.patch queue-4.14/x86-pkeys-selftests-add-a-test-for-pkey-0.patch queue-4.14/x86-pkeys-selftests-stop-using-assert.patch queue-4.14/x86-pkeys-selftests-save-off-prot-for-allocations.patch queue-4.14/x86-pkeys-selftests-remove-dead-debugging-code-fix-dprint_in_signal.patch queue-4.14/x86-mpx-selftests-adjust-the-self-test-to-fresh-distros-that-export-the-mpx-abi.patch queue-4.14/x86-pkeys-selftests-add-prot_exec-test.patch queue-4.14/x86-pkeys-selftests-allow-faults-on-unknown-keys.patch queue-4.14/x86-pkeys-selftests-give-better-unexpected-fault-error-messages.patch queue-4.14/x86-pkeys-selftests-fix-pkey-exhaustion-test-off-by-one.patch