Commit 0d4370cf authored Feb 14, 2021 by Jens Axboe

proc: don't allow async path resolution of /proc/thread-self components



If this is attempted by an io-wq kthread, then return -EOPNOTSUPP as we
don't currently support that. Once we can get task_pid_ptr() doing the
right thing, then this can go away again.

Use PF_IO_WORKER for this to speciically target the io_uring workers.
Modify the /proc/self/ check to use PF_IO_WORKER as well.

Cc: stable@vger.kernel.org
Fixes: 8d4c3e76 ("proc: don't allow async path resolution of /proc/self components")
Reported-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

parent 41be53e9

fs/proc/self.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -20,7 +20,7 @@ static const char proc_self_get_link(struct dentry dentry,
		* Not currently supported. Once we can inherit all of struct pid,
		* we can allow this.
		*/
		if (current->flags & PF_KTHREAD)
		if (current->flags & PF_IO_WORKER)
		return ERR_PTR(-EOPNOTSUPP);

		if (!tgid)

fs/proc/thread_self.c

+7 −0

Original line number	Diff line number	Diff line
		@@ -17,6 +17,13 @@ static const char proc_thread_self_get_link(struct dentry dentry,
		pid_t pid = task_pid_nr_ns(current, ns);
		char *name;

		/*
		* Not currently supported. Once we can inherit all of struct pid,
		* we can allow this.
		*/
		if (current->flags & PF_IO_WORKER)
		return ERR_PTR(-EOPNOTSUPP);

		if (!pid)
		return ERR_PTR(-ENOENT);
		name = kmalloc(10 + 6 + 10 + 1, dentry ? GFP_KERNEL : GFP_ATOMIC);