socketpair(): allocate descriptors first

simplifies failure exits considerably...

Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/socket.c b/net/socket.c
index 42d8e9c9ccd5028793ebeb27fb319911a0f4ce35..2df83c0bfde9411b879e2489535afd7168e79b0e 100644 (file)
--- a/net/socket.c
+++ b/net/socket.c
@@ -1365,88 +1365,75 @@ SYSCALL_DEFINE4(socketpair, int, family, int, type, int, protocol,
        if (SOCK_NONBLOCK != O_NONBLOCK && (flags & SOCK_NONBLOCK))
                flags = (flags & ~SOCK_NONBLOCK) | O_NONBLOCK;
 
+       /*
+        * reserve descriptors and make sure we won't fail
+        * to return them to userland.
+        */
+       fd1 = get_unused_fd_flags(flags);
+       if (unlikely(fd1 < 0))
+               return fd1;
+
+       fd2 = get_unused_fd_flags(flags);
+       if (unlikely(fd2 < 0)) {
+               put_unused_fd(fd1);
+               return fd2;
+       }
+
+       err = put_user(fd1, &usockvec[0]);
+       if (err)
+               goto out;
+
+       err = put_user(fd2, &usockvec[1]);
+       if (err)
+               goto out;
+
        /*
         * Obtain the first socket and check if the underlying protocol
         * supports the socketpair call.
         */
 
        err = sock_create(family, type, protocol, &sock1);
-       if (err < 0)
+       if (unlikely(err < 0))
                goto out;
 
        err = sock_create(family, type, protocol, &sock2);
-       if (err < 0)
-               goto out_release_1;
-
-       err = sock1->ops->socketpair(sock1, sock2);
-       if (err < 0)
-               goto out_release_both;
-
-       fd1 = get_unused_fd_flags(flags);
-       if (unlikely(fd1 < 0)) {
-               err = fd1;
-               goto out_release_both;
+       if (unlikely(err < 0)) {
+               sock_release(sock1);
+               goto out;
        }
 
-       fd2 = get_unused_fd_flags(flags);
-       if (unlikely(fd2 < 0)) {
-               err = fd2;
-               goto out_put_unused_1;
+       err = sock1->ops->socketpair(sock1, sock2);
+       if (unlikely(err < 0)) {
+               sock_release(sock2);
+               sock_release(sock1);
+               goto out;
        }
 
        newfile1 = sock_alloc_file(sock1, flags, NULL);
        if (IS_ERR(newfile1)) {
                err = PTR_ERR(newfile1);
-               goto out_put_unused_both;
+               sock_release(sock1);
+               sock_release(sock2);
+               goto out;
        }
 
        newfile2 = sock_alloc_file(sock2, flags, NULL);
        if (IS_ERR(newfile2)) {
                err = PTR_ERR(newfile2);
-               goto out_fput_1;
+               sock_release(sock2);
+               fput(newfile1);
+               goto out;
        }
 
-       err = put_user(fd1, &usockvec[0]);
-       if (err)
-               goto out_fput_both;
-
-       err = put_user(fd2, &usockvec[1]);
-       if (err)
-               goto out_fput_both;
-
        audit_fd_pair(fd1, fd2);
 
        fd_install(fd1, newfile1);
        fd_install(fd2, newfile2);
-       /* fd1 and fd2 may be already another descriptors.
-        * Not kernel problem.
-        */
-
        return 0;
 
-out_fput_both:
-       fput(newfile2);
-       fput(newfile1);
-       put_unused_fd(fd2);
-       put_unused_fd(fd1);
-       goto out;
-
-out_fput_1:
-       fput(newfile1);
-       put_unused_fd(fd2);
-       put_unused_fd(fd1);
-       sock_release(sock2);
-       goto out;
-
-out_put_unused_both:
+out:
        put_unused_fd(fd2);
-out_put_unused_1:
        put_unused_fd(fd1);
-out_release_both:
-       sock_release(sock2);
-out_release_1:
-       sock_release(sock1);
-out:
        return err;
 }