Subject: [PATCH 3/3] make sock_alloc_file() do sock_release() on failures

From: Al Viro <[email-masked]>
Date: Fri, 1 Dec 2017 00:23:26 +0000

This changes calling conventions (and simplifies the hell out
the callers).  New rules: once struct socket had been passed
to sock_alloc_file(), it's been consumed either by struct file
or by sock_release() done by sock_alloc_file().  Either way
the caller should not do sock_release() after that point.

Signed-off-by: Al Viro <[email-masked]>
---
 drivers/staging/lustre/lnet/lnet/lib-socket.c |  8 ++------
 net/9p/trans_fd.c                             |  1 -
 net/kcm/kcmsock.c                             |  7 +------
 net/sctp/socket.c                             |  1 -
 net/socket.c                                  | 25 ++++++++-----------------
 5 files changed, 11 insertions(+), 31 deletions(-)

diff --git a/drivers/staging/lustre/lnet/lnet/lib-socket.c b/drivers/staging/lustre/lnet/lnet/lib-socket.c
index 539a26444f31..7d49d4865298 100644
--- a/drivers/staging/lustre/lnet/lnet/lib-socket.c
+++ b/drivers/staging/lustre/lnet/lnet/lib-socket.c
@@ -71,16 +71,12 @@ lnet_sock_ioctl(int cmd, unsigned long arg)
 	}
 
 	sock_filp = sock_alloc_file(sock, 0, NULL);
-	if (IS_ERR(sock_filp)) {
-		sock_release(sock);
-		rc = PTR_ERR(sock_filp);
-		goto out;
-	}
+	if (IS_ERR(sock_filp))
+		return PTR_ERR(sock_filp);
 
 	rc = kernel_sock_unlocked_ioctl(sock_filp, cmd, arg);
 
 	fput(sock_filp);
-out:
 	return rc;
 }
 
diff --git a/net/9p/trans_fd.c b/net/9p/trans_fd.c
index 985046ae4231..80f5c79053a4 100644
--- a/net/9p/trans_fd.c
+++ b/net/9p/trans_fd.c
@@ -839,7 +839,6 @@ static int p9_socket_open(struct p9_client *client, struct socket *csocket)
 	if (IS_ERR(file)) {
 		pr_err("%s (%d): failed to map fd\n",
 		       __func__, task_pid_nr(current));
-		sock_release(csocket);
 		kfree(p);
 		return PTR_ERR(file);
 	}
diff --git a/net/kcm/kcmsock.c b/net/kcm/kcmsock.c
index c5fa634e63ca..d4e98f20fc2a 100644
--- a/net/kcm/kcmsock.c
+++ b/net/kcm/kcmsock.c
@@ -1629,7 +1629,6 @@ static struct file *kcm_clone(struct socket *osock)
 {
 	struct socket *newsock;
 	struct sock *newsk;
-	struct file *file;
 
 	newsock = sock_alloc();
 	if (!newsock)
@@ -1649,11 +1648,7 @@ static struct file *kcm_clone(struct socket *osock)
 	sock_init_data(newsock, newsk);
 	init_kcm_sock(kcm_sk(newsk), kcm_sk(osock->sk)->mux);
 
-	file = sock_alloc_file(newsock, 0, osock->sk->sk_prot_creator->name);
-	if (IS_ERR(file))
-		sock_release(newsock);
-
-	return file;
+	return sock_alloc_file(newsock, 0, osock->sk->sk_prot_creator->name);
 }
 
 static int kcm_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 3204a9b29407..8bb5163d6331 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -5080,7 +5080,6 @@ static int sctp_getsockopt_peeloff_common(struct sock *sk, sctp_peeloff_arg_t *p
 	*newfile = sock_alloc_file(newsock, 0, NULL);
 	if (IS_ERR(*newfile)) {
 		put_unused_fd(retval);
-		sock_release(newsock);
 		retval = PTR_ERR(*newfile);
 		*newfile = NULL;
 		return retval;
diff --git a/net/socket.c b/net/socket.c
index 2df83c0bfde9..05f361faec45 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -406,8 +406,10 @@ struct file *sock_alloc_file(struct socket *sock, int flags, const char *dname)
 		name.len = strlen(name.name);
 	}
 	path.dentry = d_alloc_pseudo(sock_mnt->mnt_sb, &name);
-	if (unlikely(!path.dentry))
+	if (unlikely(!path.dentry)) {
+		sock_release(sock);
 		return ERR_PTR(-ENOMEM);
+	}
 	path.mnt = mntget(sock_mnt);
 
 	d_instantiate(path.dentry, SOCK_INODE(sock));
@@ -415,9 +417,11 @@ struct file *sock_alloc_file(struct socket *sock, int flags, const char *dname)
 	file = alloc_file(&path, FMODE_READ | FMODE_WRITE,
 		  &socket_file_ops);
 	if (IS_ERR(file)) {
-		/* drop dentry, keep inode */
+		/* drop dentry, keep inode for a bit */
 		ihold(d_inode(path.dentry));
 		path_put(&path);
+		/* ... and now kill it properly */
+		sock_release(sock);
 		return file;
 	}
 
@@ -1330,19 +1334,9 @@ SYSCALL_DEFINE3(socket, int, family, int, type, int, protocol)
 
 	retval = sock_create(family, type, protocol, &sock);
 	if (retval < 0)
-		goto out;
-
-	retval = sock_map_fd(sock, flags & (O_CLOEXEC | O_NONBLOCK));
-	if (retval < 0)
-		goto out_release;
-
-out:
-	/* It may be already another descriptor 8) Not kernel problem. */
-	return retval;
+		return retval;
 
-out_release:
-	sock_release(sock);
-	return retval;
+	return sock_map_fd(sock, flags & (O_CLOEXEC | O_NONBLOCK));
 }
 
 /*
@@ -1412,7 +1406,6 @@ SYSCALL_DEFINE4(socketpair, int, family, int, type, int, protocol,
 	newfile1 = sock_alloc_file(sock1, flags, NULL);
 	if (IS_ERR(newfile1)) {
 		err = PTR_ERR(newfile1);
-		sock_release(sock1);
 		sock_release(sock2);
 		goto out;
 	}
@@ -1420,7 +1413,6 @@ SYSCALL_DEFINE4(socketpair, int, family, int, type, int, protocol,
 	newfile2 = sock_alloc_file(sock2, flags, NULL);
 	if (IS_ERR(newfile2)) {
 		err = PTR_ERR(newfile2);
-		sock_release(sock2);
 		fput(newfile1);
 		goto out;
 	}
@@ -1549,7 +1541,6 @@ SYSCALL_DEFINE4(accept4, int, fd, struct sockaddr __user *, upeer_sockaddr,
 	if (IS_ERR(newfile)) {
 		err = PTR_ERR(newfile);
 		put_unused_fd(newfd);
-		sock_release(newsock);
 		goto out_put;
 	}
 
-- 
2.11.0