[Devel] [PATCH hci-8.1 1/2] selftests/futex: run futex_waitv argument checks with a valid waitv

[Eva Kurchatova <eva.kurchatova@virtuozzo.com>]

The argument checks reuse the waitv[] the shared subtest leaves behind,
whose entries point into detached memory, and the invalid clockid
check passes NULL waiters. So the kernel can reject a call for a
reason other than the one tested. This goes unnoticed while the checks
accept any result.

Reset waitv[] to valid private futexes before the checks and pass it to
the clockid check.

Fixes: 5e59c1d1c78c ("selftests: futex: Add sys_futex_waitv() test")
https://virtuozzo.atlassian.net/browse/VSTOR-152660
Feature: fix selftests

Signed-off-by: Eva Kurchatova <eva.kurchatova@virtuozzo.com>
---
 .../selftests/futex/functional/futex_waitv.c  | 26 ++++++++++++++-----
 1 file changed, 19 insertions(+), 7 deletions(-)

diff --git a/tools/testing/selftests/futex/functional/futex_waitv.c b/tools/testing/selftests/futex/functional/futex_waitv.c
index 3706a32102c6..98edb25690d9 100644
--- a/tools/testing/selftests/futex/functional/futex_waitv.c
+++ b/tools/testing/selftests/futex/functional/futex_waitv.c
@@ -69,6 +69,18 @@ static int join_waiter(pthread_t waiter)
 	return failed != NULL;
 }
 
+static void set_private_waitv(void)
+{
+	int i;
+
+	for (i = 0; i < NR_FUTEXES; i++) {
+		waitv[i].uaddr = (uintptr_t)&futexes[i];
+		waitv[i].flags = FUTEX_32 | FUTEX_PRIVATE_FLAG;
+		waitv[i].val = 0;
+		waitv[i].__reserved = 0;
+	}
+}
+
 int main(int argc, char *argv[])
 {
 	pthread_t waiter;
@@ -98,12 +110,7 @@ int main(int argc, char *argv[])
 	ksft_print_msg("%s: Test FUTEX_WAITV\n",
 		       basename(argv[0]));
 
-	for (i = 0; i < NR_FUTEXES; i++) {
-		waitv[i].uaddr = (uintptr_t)&futexes[i];
-		waitv[i].flags = FUTEX_32 | FUTEX_PRIVATE_FLAG;
-		waitv[i].val = 0;
-		waitv[i].__reserved = 0;
-	}
+	set_private_waitv();
 
 	/* Private waitv */
 	if (pthread_create(&waiter, NULL, waiterfn, NULL))
@@ -165,6 +172,9 @@ int main(int argc, char *argv[])
 	for (i = 0; i < NR_FUTEXES; i++)
 		shmdt(u64_to_ptr(waitv[i].uaddr));
 
+	/* Each check below breaks one argument of an otherwise valid call */
+	set_private_waitv();
+
 	/* Testing a waiter without FUTEX_32 flag */
 	waitv[0].flags = FUTEX_PRIVATE_FLAG;
 
@@ -237,12 +247,14 @@ int main(int argc, char *argv[])
 	}
 
 	/* Testing an invalid clockid */
+	waitv[0].uaddr = (uintptr_t)&futexes[0];
+
 	if (clock_gettime(CLOCK_MONOTONIC, &to))
 		error("gettime64 failed\n", errno);
 
 	to.tv_sec++;
 
-	res = futex_waitv(NULL, NR_FUTEXES, 0, &to, CLOCK_TAI);
+	res = futex_waitv(waitv, NR_FUTEXES, 0, &to, CLOCK_TAI);
 	if (res == EINVAL) {
 		ksft_test_result_fail("futex_waitv private returned: %d %s\n",
 				      res ? errno : res,
-- 
2.56.0

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