linux-kernel - [PATCH RFC 6/8] selftests: openat2: add 0xFF poisoned data after misaligned struct

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Message-Id: <20240902-extensible-structs-check_fields-v1-6-545e93ede2f2@cyphar.com>
Date: Mon, 02 Sep 2024 17:06:28 +1000
From: Aleksa Sarai <cyphar@...har.com>
To: Ingo Molnar <mingo@...hat.com>, Peter Zijlstra <peterz@...radead.org>, 
 Juri Lelli <juri.lelli@...hat.com>, 
 Vincent Guittot <vincent.guittot@...aro.org>, 
 Dietmar Eggemann <dietmar.eggemann@....com>, 
 Steven Rostedt <rostedt@...dmis.org>, Ben Segall <bsegall@...gle.com>, 
 Mel Gorman <mgorman@...e.de>, Valentin Schneider <vschneid@...hat.com>, 
 Alexander Viro <viro@...iv.linux.org.uk>, 
 Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>, 
 Arnd Bergmann <arnd@...db.de>, Shuah Khan <shuah@...nel.org>
Cc: Kees Cook <kees@...nel.org>, Florian Weimer <fweimer@...hat.com>, 
 Arnd Bergmann <arnd@...db.de>, Mark Rutland <mark.rutland@....com>, 
 linux-kernel@...r.kernel.org, linux-api@...r.kernel.org, 
 linux-fsdevel@...r.kernel.org, linux-arch@...r.kernel.org, 
 linux-kselftest@...r.kernel.org, Aleksa Sarai <cyphar@...har.com>
Subject: [PATCH RFC 6/8] selftests: openat2: add 0xFF poisoned data after
 misaligned struct

We should also verify that poisoned data after a misaligned struct is
also handled correctly by is_zeroed_user(). This test passes with no
kernel changes needed, so is_zeroed_user() was correct already.

Fixes: b28a10aedcd4 ("selftests: add openat2(2) selftests")
Signed-off-by: Aleksa Sarai <cyphar@...har.com>
---
 tools/testing/selftests/openat2/openat2_test.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/openat2/openat2_test.c b/tools/testing/selftests/openat2/openat2_test.c
index 5790ab446527..4ca175a16ad6 100644
--- a/tools/testing/selftests/openat2/openat2_test.c
+++ b/tools/testing/selftests/openat2/openat2_test.c
@@ -112,9 +112,9 @@ void test_openat2_struct(void)
 				 *
 				 * This is effectively to check that is_zeroed_user() works.
 				 */
-				copy = malloc(misalign + sizeof(how_ext));
+				copy = malloc(misalign*2 + sizeof(how_ext));
 				how_copy = copy + misalign;
-				memset(copy, 0xff, misalign);
+				memset(copy, 0xff, misalign*2 + sizeof(how_ext));
 				memcpy(how_copy, &how_ext, sizeof(how_ext));
 			}
 

-- 
2.46.0