Commit 0658a096 authored by Florian Weimer's avatar Florian Weimer Committed by Linus Torvalds

procfs: do not list TID 0 in /proc/<pid>/task

If a task exits concurrently, task_pid_nr_ns may return 0.

[akpm@linux-foundation.org: coding style tweaks]
[adobriyan@gmail.com: 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@oldenburg.str.redhat.comSigned-off-by: default avatarFlorian Weimer <fweimer@redhat.com>
Signed-off-by: default avatarAlexey Dobriyan <adobriyan@gmail.com>
Acked-by: default avatarChristian Brauner <christian.brauner@ubuntu.com>
Reviewed-by: default avatarAlexey Dobriyan <adobriyan@gmail.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 83c1fd76
......@@ -3799,7 +3799,10 @@ static int proc_task_readdir(struct file *file, struct dir_context *ctx)
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)) {
......
......@@ -11,6 +11,7 @@
/proc-self-syscall
/proc-self-wchan
/proc-subset-pid
/proc-tid0
/proc-uptime-001
/proc-uptime-002
/read
......
# 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-002
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
......
/*
* Copyright (c) 2021 Alexey Dobriyan <adobriyan@gmail.com>
*
* 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;
}
}
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