nsfs: use cleanup guard

Ensure that rcu read lock is given up before returning.

Link: https://lore.kernel.org/r/20240716-elixier-fliesen-1ab342151a61@brauner
Fixes: ca567df74a28 ("nsfs: add pid translation ioctls")
Reported-by: syzbot+a3e82ae343b26b4d2335@syzkaller.appspotmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/fs/nsfs.c b/fs/nsfs.c
index a4a925dce33127fc6ccd107f500338cf141e1ab3..97c37a9631e5515c1f66728ea1b9576cbff77cba 100644 (file)
--- a/fs/nsfs.c
+++ b/fs/nsfs.c
@@ -174,14 +174,14 @@ static long ns_ioctl(struct file *filp, unsigned int ioctl,
                fallthrough;
        case NS_GET_PID_IN_PIDNS:
                fallthrough;
-       case NS_GET_TGID_IN_PIDNS:
+       case NS_GET_TGID_IN_PIDNS: {
                if (ns->ops->type != CLONE_NEWPID)
                        return -EINVAL;
 
                ret = -ESRCH;
                pid_ns = container_of(ns, struct pid_namespace, ns);
 
-               rcu_read_lock();
+               guard(rcu)();
 
                if (ioctl == NS_GET_PID_IN_PIDNS ||
                    ioctl == NS_GET_TGID_IN_PIDNS)
@@ -208,11 +208,11 @@ static long ns_ioctl(struct file *filp, unsigned int ioctl,
                        ret = 0;
                        break;
                }
-               rcu_read_unlock();
 
                if (!ret)
                        ret = -ESRCH;
                break;
+       }
        default:
                ret = -ENOTTY;
        }