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authorFrank Filz <ffilzlnx@us.ibm.com>2005-09-27 15:23:38 -0700
committerDavid S. Miller <davem@davemloft.net>2005-09-27 15:23:38 -0700
commita79af59efd20990473d579b1d8d70bb120f0920c (patch)
tree763cc7f083cf922e30537c89d92765415ada78e4 /net/core/sock.c
parent9356b8fc07dc126cd91d2b12f314d760ab48996e (diff)
[NET]: Fix module reference counts for loadable protocol modules
I have been experimenting with loadable protocol modules, and ran into several issues with module reference counting. The first issue was that __module_get failed at the BUG_ON check at the top of the routine (checking that my module reference count was not zero) when I created the first socket. When sk_alloc() is called, my module reference count was still 0. When I looked at why sctp didn't have this problem, I discovered that sctp creates a control socket during module init (when the module ref count is not 0), which keeps the reference count non-zero. This section has been updated to address the point Stephen raised about checking the return value of try_module_get(). The next problem arose when my socket init routine returned an error. This resulted in my module reference count being decremented below 0. My socket ops->release routine was also being called. The issue here is that sock_release() calls the ops->release routine and decrements the ref count if sock->ops is not NULL. Since the socket probably didn't get correctly initialized, this should not be done, so we will set sock->ops to NULL because we will not call try_module_get(). While searching for another bug, I also noticed that sys_accept() has a possibility of doing a module_put() when it did not do an __module_get so I re-ordered the call to security_socket_accept(). Signed-off-by: Frank Filz <ffilzlnx@us.ibm.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core/sock.c')
-rw-r--r--net/core/sock.c20
1 files changed, 12 insertions, 8 deletions
diff --git a/net/core/sock.c b/net/core/sock.c
index ac63b56e23b..928d2a1d6d8 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -660,16 +660,20 @@ struct sock *sk_alloc(int family, unsigned int __nocast priority,
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)