lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20230828150858.393570-3-revest@chromium.org>
Date:   Mon, 28 Aug 2023 17:08:54 +0200
From:   Florent Revest <revest@...omium.org>
To:     linux-kernel@...r.kernel.org, linux-mm@...ck.org
Cc:     akpm@...ux-foundation.org, catalin.marinas@....com,
        anshuman.khandual@....com, joey.gouly@....com, mhocko@...e.com,
        keescook@...omium.org, david@...hat.com, peterx@...hat.com,
        izbyshev@...ras.ru, broonie@...nel.org, szabolcs.nagy@....com,
        kpsingh@...nel.org, gthelen@...gle.com, toiwoton@...il.com,
        ayush.jain3@....com, Florent Revest <revest@...omium.org>,
        Ryan Roberts <ryan.roberts@....com>
Subject: [PATCH v4 2/6] kselftest: vm: Fix mdwe's mmap_FIXED test case

I checked with the original author, the mmap_FIXED test case wasn't
properly tested and fails. Currently, it maps two consecutive (non
overlapping) pages and expects the second mapping to be denied by MDWE
but these two pages have nothing to do with each other so MDWE is
actually out of the picture here.

What the test actually intended to do was to remap a virtual address
using MAP_FIXED. However, this operation unmaps the existing mapping and
creates a new one so the va is backed by a new page and MDWE is again
out of the picture, all remappings should succeed.

This patch keeps the test case to make it clear that this situation is
expected to work: MDWE shouldn't block a MAP_FIXED replacement.

Signed-off-by: Florent Revest <revest@...omium.org>
Reviewed-by: David Hildenbrand <david@...hat.com>
Reviewed-by: Kees Cook <keescook@...omium.org>
Reviewed-by: Catalin Marinas <catalin.marinas@....com>
Reviewed-by: Ryan Roberts <ryan.roberts@....com>
Tested-by: Ryan Roberts <ryan.roberts@....com>
Tested-by: Ayush Jain <ayush.jain3@....com>
Fixes: 4cf1fe34fd18 ("kselftest: vm: add tests for memory-deny-write-execute")
---
 tools/testing/selftests/mm/mdwe_test.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/tools/testing/selftests/mm/mdwe_test.c b/tools/testing/selftests/mm/mdwe_test.c
index d0954c657feb..91aa9c3099e7 100644
--- a/tools/testing/selftests/mm/mdwe_test.c
+++ b/tools/testing/selftests/mm/mdwe_test.c
@@ -168,13 +168,10 @@ TEST_F(mdwe, mmap_FIXED)
 	self->p = mmap(NULL, self->size, PROT_READ, self->flags, 0, 0);
 	ASSERT_NE(self->p, MAP_FAILED);
 
-	p = mmap(self->p + self->size, self->size, PROT_READ | PROT_EXEC,
+	/* MAP_FIXED unmaps the existing page before mapping which is allowed */
+	p = mmap(self->p, self->size, PROT_READ | PROT_EXEC,
 		 self->flags | MAP_FIXED, 0, 0);
-	if (variant->enabled) {
-		EXPECT_EQ(p, MAP_FAILED);
-	} else {
-		EXPECT_EQ(p, self->p);
-	}
+	EXPECT_EQ(p, self->p);
 }
 
 TEST_F(mdwe, arm64_BTI)
-- 
2.42.0.rc2.253.gd59a3bf2b4-goog

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ