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authorKuniyuki Iwashima <kuniyu@amazon.co.jp>2021-09-28 09:42:27 +0900
committerDavid S. Miller <davem@davemloft.net>2021-09-28 13:22:57 +0100
commitf4bd73b5a950866f6c6fc98a7b684d307c5d586a (patch)
treeae8184e77f0e5436c280ade82a213dac64c1e264 /net/unix
parenta9f5970767d11eadc805d5283f202612c7ba1f59 (diff)
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af_unix: Return errno instead of NULL in unix_create1().
unix_create1() returns NULL on error, and the callers assume that it never fails for reasons other than out of memory. So, the callers always return -ENOMEM when unix_create1() fails. However, it also returns NULL when the number of af_unix sockets exceeds twice the limit controlled by sysctl: fs.file-max. In this case, the callers should return -ENFILE like alloc_empty_file(). This patch changes unix_create1() to return the correct error value instead of NULL on error. Out of curiosity, the assumption has been wrong since 1999 due to this change introduced in 2.2.4 [0]. diff -u --recursive --new-file v2.2.3/linux/net/unix/af_unix.c linux/net/unix/af_unix.c --- v2.2.3/linux/net/unix/af_unix.c Tue Jan 19 11:32:53 1999 +++ linux/net/unix/af_unix.c Sun Mar 21 07:22:00 1999 @@ -388,6 +413,9 @@ { struct sock *sk; + if (atomic_read(&unix_nr_socks) >= 2*max_files) + return NULL; + MOD_INC_USE_COUNT; sk = sk_alloc(PF_UNIX, GFP_KERNEL, 1); if (!sk) { [0]: https://cdn.kernel.org/pub/linux/kernel/v2.2/patch-2.2.4.gz Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/unix')
-rw-r--r--net/unix/af_unix.c49
1 files changed, 32 insertions, 17 deletions
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 92345c9bb60c..f505b89bda6a 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -828,20 +828,25 @@ struct proto unix_stream_proto = {
static struct sock *unix_create1(struct net *net, struct socket *sock, int kern, int type)
{
- struct sock *sk = NULL;
struct unix_sock *u;
+ struct sock *sk;
+ int err;
atomic_long_inc(&unix_nr_socks);
- if (atomic_long_read(&unix_nr_socks) > 2 * get_max_files())
- goto out;
+ if (atomic_long_read(&unix_nr_socks) > 2 * get_max_files()) {
+ err = -ENFILE;
+ goto err;
+ }
if (type == SOCK_STREAM)
sk = sk_alloc(net, PF_UNIX, GFP_KERNEL, &unix_stream_proto, kern);
else /*dgram and seqpacket */
sk = sk_alloc(net, PF_UNIX, GFP_KERNEL, &unix_dgram_proto, kern);
- if (!sk)
- goto out;
+ if (!sk) {
+ err = -ENOMEM;
+ goto err;
+ }
sock_init_data(sock, sk);
@@ -861,20 +866,23 @@ static struct sock *unix_create1(struct net *net, struct socket *sock, int kern,
init_waitqueue_func_entry(&u->peer_wake, unix_dgram_peer_wake_relay);
memset(&u->scm_stat, 0, sizeof(struct scm_stat));
unix_insert_socket(unix_sockets_unbound(sk), sk);
-out:
- if (sk == NULL)
- atomic_long_dec(&unix_nr_socks);
- else {
- local_bh_disable();
- sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
- local_bh_enable();
- }
+
+ local_bh_disable();
+ sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
+ local_bh_enable();
+
return sk;
+
+err:
+ atomic_long_dec(&unix_nr_socks);
+ return ERR_PTR(err);
}
static int unix_create(struct net *net, struct socket *sock, int protocol,
int kern)
{
+ struct sock *sk;
+
if (protocol && protocol != PF_UNIX)
return -EPROTONOSUPPORT;
@@ -901,7 +909,11 @@ static int unix_create(struct net *net, struct socket *sock, int protocol,
return -ESOCKTNOSUPPORT;
}
- return unix_create1(net, sock, kern, sock->type) ? 0 : -ENOMEM;
+ sk = unix_create1(net, sock, kern, sock->type);
+ if (IS_ERR(sk))
+ return PTR_ERR(sk);
+
+ return 0;
}
static int unix_release(struct socket *sock)
@@ -1314,12 +1326,15 @@ static int unix_stream_connect(struct socket *sock, struct sockaddr *uaddr,
we will have to recheck all again in any case.
*/
- err = -ENOMEM;
-
/* create new sock for complete connection */
newsk = unix_create1(sock_net(sk), NULL, 0, sock->type);
- if (newsk == NULL)
+ if (IS_ERR(newsk)) {
+ err = PTR_ERR(newsk);
+ newsk = NULL;
goto out;
+ }
+
+ err = -ENOMEM;
/* Allocate skb for sending to listening sock */
skb = sock_wmalloc(newsk, 1, 0, GFP_KERNEL);