@@ -66,6 +66,8 @@
#include <sys/wait.h>
#include <unistd.h>
#include <setjmp.h>
+#include <syscall.h>
+#include <linux/sched.h>
#include "kselftest.h"
@@ -80,6 +82,17 @@
# define TH_LOG_ENABLED 1
#endif
+/* Wait for the child process to end but without sharing memory mapping. */
+static inline pid_t clone3_vfork(void)
+{
+ struct clone_args args = {
+ .flags = CLONE_VFORK,
+ .exit_signal = SIGCHLD,
+ };
+
+ return syscall(__NR_clone3, &args, sizeof(args));
+}
+
/**
* TH_LOG()
*
@@ -1183,7 +1196,7 @@ void __run_test(struct __fixture_metadata *f,
fflush(stdout);
fflush(stderr);
- t->pid = fork();
+ t->pid = clone3_vfork();
if (t->pid < 0) {
ksft_print_msg("ERROR SPAWNING TEST CHILD\n");
t->exit_code = KSFT_FAIL;
Fix a race condition when running several FIXTURE_TEARDOWN() managing the same resource. This fixes a race condition in the Landlock file system tests when creating or unmounting the same directory. Using clone3() with CLONE_VFORK guarantees that the child and grandchild test processes are sequentially scheduled. This is implemented with a new clone3_vfork() helper replacing the fork() call. This avoids triggering this error in __wait_for_test(): Test ended in some other way [127] Cc: Christian Brauner <brauner@kernel.org> Cc: David S. Miller <davem@davemloft.net> Cc: Günther Noack <gnoack@google.com> Cc: Jakub Kicinski <kuba@kernel.org> Cc: Mark Brown <broonie@kernel.org> Cc: Shuah Khan <shuah@kernel.org> Cc: Will Drewry <wad@chromium.org> Fixes: 41cca0542d7c ("selftests/harness: Fix TEST_F()'s vfork handling") Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: Mickaël Salaün <mic@digikod.net> Link: https://lore.kernel.org/r/20240429191911.2552580-5-mic@digikod.net --- Changes since v2: * Replace __attribute__((__unused__)) with inline for clone3_vfork() (suggested by Kees and Jakub) --- tools/testing/selftests/kselftest_harness.h | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-)