The patch titled
Subject: procfs: do not list TID 0 in /proc/<pid>/task
has been removed from the -mm tree. Its filename was
procfs-do-not-list-tid-0-in-proc-pid-task.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Florian Weimer <fweimer@xxxxxxxxxx>
Subject: procfs: do not list TID 0 in /proc/<pid>/task
If a task exits concurrently, task_pid_nr_ns may return 0.
[akpm@xxxxxxxxxxxxxxxxxxxx: coding style tweaks]
[adobriyan@xxxxxxxxx: test that /proc/*/task doesn't contain "0"]
Link: https://lkml.kernel.org/r/YV88AnVzHxPafQ9o@localhost.localdomain
Link: https://lkml.kernel.org/r/8735pn5dx7.fsf@xxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Florian Weimer <fweimer@xxxxxxxxxx>
Signed-off-by: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Acked-by: Christian Brauner <christian.brauner@xxxxxxxxxx>
Reviewed-by: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/proc/base.c | 3
tools/testing/selftests/proc/.gitignore | 1
tools/testing/selftests/proc/Makefile | 2
tools/testing/selftests/proc/proc-tid0.c | 81 +++++++++++++++++++++
4 files changed, 87 insertions(+)
--- a/fs/proc/base.c~procfs-do-not-list-tid-0-in-proc-pid-task
+++ a/fs/proc/base.c
@@ -3799,7 +3799,10 @@ static int proc_task_readdir(struct file
task = next_tid(task), ctx->pos++) {
char name[10 + 1];
unsigned int len;
+
tid = task_pid_nr_ns(task, ns);
+ if (!tid)
+ continue; /* The task has just exited. */
len = snprintf(name, sizeof(name), "%u", tid);
if (!proc_fill_cache(file, ctx, name, len,
proc_task_instantiate, task, NULL)) {
--- a/tools/testing/selftests/proc/.gitignore~procfs-do-not-list-tid-0-in-proc-pid-task
+++ a/tools/testing/selftests/proc/.gitignore
@@ -11,6 +11,7 @@
/proc-self-syscall
/proc-self-wchan
/proc-subset-pid
+/proc-tid0
/proc-uptime-001
/proc-uptime-002
/read
--- a/tools/testing/selftests/proc/Makefile~procfs-do-not-list-tid-0-in-proc-pid-task
+++ a/tools/testing/selftests/proc/Makefile
@@ -1,6 +1,7 @@
# SPDX-License-Identifier: GPL-2.0-only
CFLAGS += -Wall -O2 -Wno-unused-function
CFLAGS += -D_GNU_SOURCE
+LDFLAGS += -pthread
TEST_GEN_PROGS :=
TEST_GEN_PROGS += fd-001-lookup
@@ -13,6 +14,7 @@ TEST_GEN_PROGS += proc-self-map-files-00
TEST_GEN_PROGS += proc-self-syscall
TEST_GEN_PROGS += proc-self-wchan
TEST_GEN_PROGS += proc-subset-pid
+TEST_GEN_PROGS += proc-tid0
TEST_GEN_PROGS += proc-uptime-001
TEST_GEN_PROGS += proc-uptime-002
TEST_GEN_PROGS += read
--- /dev/null
+++ a/tools/testing/selftests/proc/proc-tid0.c
@@ -0,0 +1,81 @@
+/*
+ * Copyright (c) 2021 Alexey Dobriyan <adobriyan@xxxxxxxxx>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+// Test that /proc/*/task never contains "0".
+#include <sys/types.h>
+#include <dirent.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <pthread.h>
+
+static pid_t pid = -1;
+
+static void atexit_hook(void)
+{
+ if (pid > 0) {
+ kill(pid, SIGKILL);
+ }
+}
+
+static void *f(void *_)
+{
+ return NULL;
+}
+
+static void sigalrm(int _)
+{
+ exit(0);
+}
+
+int main(void)
+{
+ pid = fork();
+ if (pid == 0) {
+ /* child */
+ while (1) {
+ pthread_t pth;
+ pthread_create(&pth, NULL, f, NULL);
+ pthread_join(pth, NULL);
+ }
+ } else if (pid > 0) {
+ /* parent */
+ atexit(atexit_hook);
+
+ char buf[64];
+ snprintf(buf, sizeof(buf), "/proc/%u/task", pid);
+
+ signal(SIGALRM, sigalrm);
+ alarm(1);
+
+ while (1) {
+ DIR *d = opendir(buf);
+ struct dirent *de;
+ while ((de = readdir(d))) {
+ if (strcmp(de->d_name, "0") == 0) {
+ exit(1);
+ }
+ }
+ closedir(d);
+ }
+
+ return 0;
+ } else {
+ perror("fork");
+ return 1;
+ }
+}
_
Patches currently in -mm which might be from fweimer@xxxxxxxxxx are
