On Mon, 2005-08-29 at 16:45 -0700, Stephen Hemminger wrote:
> You must check return value from try_module_get and error out
> if it fails. This is critical for module unload races.
Good point, and of course in such a situation, sk_alloc must
free the socket. Please see the updated patch below.
Thanks
Frank
---
Signed-off-by: Frank Filz <[EMAIL PROTECTED]>
diff --git a/net/core/sock.c b/net/core/sock.c
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -660,16 +660,20 @@ struct sock *sk_alloc(int family, unsign
sock_lock_init(sk);
}
- if (security_sk_alloc(sk, family, priority)) {
- if (slab != NULL)
- kmem_cache_free(slab, sk);
- else
- kfree(sk);
- sk = NULL;
- } else
- __module_get(prot->owner);
+ if (security_sk_alloc(sk, family, priority))
+ goto out_free;
+
+ if (!try_module_get(prot->owner))
+ goto out_free;
}
return sk;
+
+out_free:
+ if (slab != NULL)
+ kmem_cache_free(slab, sk);
+ else
+ kfree(sk);
+ return NULL;
}
void sk_free(struct sock *sk)
diff --git a/net/socket.c b/net/socket.c
--- a/net/socket.c
+++ b/net/socket.c
@@ -1145,8 +1145,11 @@ static int __sock_create(int family, int
if (!try_module_get(net_families[family]->owner))
goto out_release;
- if ((err = net_families[family]->create(sock, protocol)) < 0)
+ if ((err = net_families[family]->create(sock, protocol)) < 0) {
+ sock->ops = NULL;
goto out_module_put;
+ }
+
/*
* Now to bump the refcnt of the [loadable] module that owns this
* socket at sock_release time we decrement its refcnt.
@@ -1360,16 +1363,16 @@ asmlinkage long sys_accept(int fd, struc
newsock->type = sock->type;
newsock->ops = sock->ops;
- err = security_socket_accept(sock, newsock);
- if (err)
- goto out_release;
-
/*
* We don't need try_module_get here, as the listening socket (sock)
* has the protocol module (sock->ops->owner) held.
*/
__module_get(newsock->ops->owner);
+ err = security_socket_accept(sock, newsock);
+ if (err)
+ goto out_release;
+
err = sock->ops->accept(sock, newsock, sock->file->f_flags);
if (err < 0)
goto out_release;
-
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