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

[ Upstream commit 8d4c3e76e3be11a64df95ddee52e99092d42fc19 ]

If this is attempted by a 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.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/fs/proc/self.c b/fs/proc/self.c
index 2dcc2558b3aa78cc4c5521849c2cd718739c6198..dffbe533d53fc7f6bc478f084d15dae48e0639af 100644 (file)
--- a/fs/proc/self.c
+++ b/fs/proc/self.c
@@ -24,6 +24,13 @@ static const char *proc_self_follow_link(struct dentry *dentry, void **cookie)
        pid_t tgid = task_tgid_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_KTHREAD)
+               return ERR_PTR(-EOPNOTSUPP);
+
        if (!tgid)
                return ERR_PTR(-ENOENT);
        /* 11 for max length of signed int in decimal + NULL term */