Patch "x86/pkeys/selftests: Add a test for pkey 0" has been added to the 4.16-stable tree

[<gregkh@linuxfoundation.org>]

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 4.16-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-4.16 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Sun Jun 17 12:07:34 CEST 2018
From: Dave Hansen <dave.hansen@linux.intel.com>
Date: Wed, 9 May 2018 10:13:56 -0700
Subject: x86/pkeys/selftests: Add a test for pkey 0

From: Dave Hansen <dave.hansen@linux.intel.com>

[ 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.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Ellermen <mpe@ellerman.id.au>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ram Pai <linuxram@us.ibm.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20180509171356.9E40B254@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 tools/testing/selftests/x86/protection_keys.c |   30 ++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

--- a/tools/testing/selftests/x86/protection_keys.c
+++ b/tools/testing/selftests/x86/protection_keys.c
@@ -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 dave.hansen@linux.intel.com are

queue-4.16/x86-pkeys-selftests-factor-out-instruction-page.patch
queue-4.16/x86-pkeys-selftests-fix-pointer-math.patch
queue-4.16/x86-pkeys-selftests-adjust-the-self-test-to-fresh-distros-that-export-the-pkeys-abi.patch
queue-4.16/x86-pkeys-selftests-add-a-test-for-pkey-0.patch
queue-4.16/x86-pkeys-selftests-stop-using-assert.patch
queue-4.16/x86-pkeys-selftests-save-off-prot-for-allocations.patch
queue-4.16/x86-pkeys-selftests-remove-dead-debugging-code-fix-dprint_in_signal.patch
queue-4.16/x86-mpx-selftests-adjust-the-self-test-to-fresh-distros-that-export-the-mpx-abi.patch
queue-4.16/x86-pkeys-selftests-add-prot_exec-test.patch
queue-4.16/x86-pkeys-selftests-allow-faults-on-unknown-keys.patch
queue-4.16/x86-pkeys-selftests-give-better-unexpected-fault-error-messages.patch
queue-4.16/x86-pkeys-selftests-avoid-printf-in-signal-deadlocks.patch
queue-4.16/x86-pkeys-selftests-fix-pkey-exhaustion-test-off-by-one.patch