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

commit 0d4370cfe36b7f1719123b621a4ec4d9c7a25f89 upstream.

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: 8d4c3e76e3be ("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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/proc/self.c b/fs/proc/self.c
index cc71ce3..a401215 100644 (file)
--- a/fs/proc/self.c
+++ b/fs/proc/self.c
@@ -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)

diff --git a/fs/proc/thread_self.c b/fs/proc/thread_self.c
index a553273..d56681d 100644 (file)
--- a/fs/proc/thread_self.c
+++ b/fs/proc/thread_self.c
@@ -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);