From 8a46067783bdff222d1fb8f8c20e3b7b711e3ce5 Mon Sep 17 00:00:00 2001
From: Christian Brauner <brauner@kernel.org>
Date: Thu, 26 Sep 2024 18:51:46 +0200
Subject: pidfs: check for valid pid namespace
When we access a no-current task's pid namespace we need check that the
task hasn't been reaped in the meantime and it's pid namespace isn't
accessible anymore.
The user namespace is fine because it is only released when the last
reference to struct task_struct is put and exit_creds() is called.
Link: https://lore.kernel.org/r/20240926-klebt-altgedienten-0415ad4d273c@brauner
Fixes: 5b08bd408534 ("pidfs: allow retrieval of namespace file descriptors")
CC: stable@vger.kernel.org # v6.11
Signed-off-by: Christian Brauner <brauner@kernel.org>
---
fs/pidfs.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
(limited to 'fs')
diff --git a/fs/pidfs.c b/fs/pidfs.c
index 7ffdc88dfb52..80675b6bf884 100644
--- a/fs/pidfs.c
+++ b/fs/pidfs.c
@@ -120,6 +120,7 @@ static long pidfd_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
struct nsproxy *nsp __free(put_nsproxy) = NULL;
struct pid *pid = pidfd_pid(file);
struct ns_common *ns_common = NULL;
+ struct pid_namespace *pid_ns;
if (arg)
return -EINVAL;
@@ -202,7 +203,9 @@ static long pidfd_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
case PIDFD_GET_PID_NAMESPACE:
if (IS_ENABLED(CONFIG_PID_NS)) {
rcu_read_lock();
- ns_common = to_ns_common( get_pid_ns(task_active_pid_ns(task)));
+ pid_ns = task_active_pid_ns(task);
+ if (pid_ns)
+ ns_common = to_ns_common(get_pid_ns(pid_ns));
rcu_read_unlock();
}
break;
--
cgit