[PATCH 2/8] unix_bind(): allocate addr earlier

[Al Viro]

>From 24439dbb7b78cb301c73254b364020e6a3f31902 Mon Sep 17 00:00:00 2001
From: Al Viro <v...@zeniv.linux.org.uk>
Date: Thu, 18 Feb 2021 15:52:53 -0500
Subject: [PATCH 2/8] unix_bind(): allocate addr earlier

makes it easier to massage; we do pay for that by extra work
(kmalloc+memcpy+kfree) in some error cases, but those are not
on the hot paths anyway.

Signed-off-by: Al Viro <v...@zeniv.linux.org.uk>
---
 net/unix/af_unix.c | 26 ++++++++++++++------------
 1 file changed, 14 insertions(+), 12 deletions(-)

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 179b4fe837e6..451d81f405c0 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -1039,6 +1039,15 @@ static int unix_bind(struct socket *sock, struct 
sockaddr *uaddr, int addr_len)
        if (err < 0)
                goto out;
        addr_len = err;
+       err = -ENOMEM;
+       addr = kmalloc(sizeof(*addr)+addr_len, GFP_KERNEL);
+       if (!addr)
+               goto out;
+
+       memcpy(addr->name, sunaddr, addr_len);
+       addr->len = addr_len;
+       addr->hash = hash ^ sk->sk_type;
+       refcount_set(&addr->refcnt, 1);
 
        if (sun_path[0]) {
                umode_t mode = S_IFSOCK |
@@ -1047,7 +1056,7 @@ static int unix_bind(struct socket *sock, struct sockaddr 
*uaddr, int addr_len)
                if (err) {
                        if (err == -EEXIST)
                                err = -EADDRINUSE;
-                       goto out;
+                       goto out_addr;
                }
        }
 
@@ -1059,16 +1068,6 @@ static int unix_bind(struct socket *sock, struct 
sockaddr *uaddr, int addr_len)
        if (u->addr)
                goto out_up;
 
-       err = -ENOMEM;
-       addr = kmalloc(sizeof(*addr)+addr_len, GFP_KERNEL);
-       if (!addr)
-               goto out_up;
-
-       memcpy(addr->name, sunaddr, addr_len);
-       addr->len = addr_len;
-       addr->hash = hash ^ sk->sk_type;
-       refcount_set(&addr->refcnt, 1);
-
        if (sun_path[0]) {
                addr->hash = UNIX_HASH_SIZE;
                hash = d_backing_inode(path.dentry)->i_ino & (UNIX_HASH_SIZE - 
1);
@@ -1080,19 +1079,22 @@ static int unix_bind(struct socket *sock, struct 
sockaddr *uaddr, int addr_len)
                if (__unix_find_socket_byname(net, sunaddr, addr_len,
                                              sk->sk_type, hash)) {
                        spin_unlock(&unix_table_lock);
-                       unix_release_addr(addr);
                        goto out_up;
                }
                hash = addr->hash;
        }
 
        __unix_set_addr(sk, addr, hash);
+       addr = NULL;
        err = 0;
 out_up:
        mutex_unlock(&u->bindlock);
 out_put:
        if (err)
                path_put(&path);
+out_addr:
+       if (addr)
+               unix_release_addr(addr);
 out:
        return err;
 }
-- 
2.11.0