net-2.6 [Bug-Fix][dccp]: fix oops caused after failed initialisation

dccp: fix panic caused by failed initialisation

This fixes a kernel panic reported thanks to Andre Noll:

if DCCP is compiled into the kernel and any out of the initialisation
steps in net/dccp/proto.c:dccp_init() fail, a subsequent attempt to create
a SOCK_DCCP socket will panic, since inet{,6}_create() are not prevented
from creating DCCP sockets.

This patch fixes the problem by propagating a failure in dccp_init() to
dccp_v{4,6}_init_net(), and from there to dccp_v{4,6}_init(), so that the
DCCP protocol is not made available if its initialisation fails.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 17 insertions, 15 deletions

diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c
index b195c4feaa0..4071eaf2b36 100644
--- a/net/dccp/ipv4.c
+++ b/net/dccp/ipv4.c
@@ -998,11 +998,11 @@ static struct inet_protosw dccp_v4_protosw = {
 
 static int __net_init dccp_v4_init_net(struct net *net)
 {
-        int err;
+        if (dccp_hashinfo.bhash == NULL)
+                return -ESOCKTNOSUPPORT;
 
-        err = inet_ctl_sock_create(&net->dccp.v4_ctl_sk, PF_INET,
-                                   SOCK_DCCP, IPPROTO_DCCP, net);
-        return err;
+        return inet_ctl_sock_create(&net->dccp.v4_ctl_sk, PF_INET,
+                                    SOCK_DCCP, IPPROTO_DCCP, net);
 }
 
 static void __net_exit dccp_v4_exit_net(struct net *net)
diff --git a/net/dccp/ipv6.c b/net/dccp/ipv6.c
index 1aec6349e85..af3394df63b 100644
--- a/net/dccp/ipv6.c
+++ b/net/dccp/ipv6.c
@@ -1191,11 +1191,11 @@ static struct inet_protosw dccp_v6_protosw = {
 
 static int __net_init dccp_v6_init_net(struct net *net)
 {
-        int err;
+        if (dccp_hashinfo.bhash == NULL)
+                return -ESOCKTNOSUPPORT;
 
-        err = inet_ctl_sock_create(&net->dccp.v6_ctl_sk, PF_INET6,
-                                   SOCK_DCCP, IPPROTO_DCCP, net);
-        return err;
+        return inet_ctl_sock_create(&net->dccp.v6_ctl_sk, PF_INET6,
+                                    SOCK_DCCP, IPPROTO_DCCP, net);
 }
 
 static void __net_exit dccp_v6_exit_net(struct net *net)
diff --git a/net/dccp/proto.c b/net/dccp/proto.c
index 0ef7061920c..aa4cef374fd 100644
--- a/net/dccp/proto.c
+++ b/net/dccp/proto.c
@@ -1036,7 +1036,7 @@ static int __init dccp_init(void)
                      FIELD_SIZEOF(struct sk_buff, cb));
         rc = percpu_counter_init(&dccp_orphan_count, 0);
         if (rc)
-                goto out;
+                goto out_fail;
         rc = -ENOBUFS;
         inet_hashinfo_init(&dccp_hashinfo);
         dccp_hashinfo.bind_bucket_cachep =
@@ -1125,8 +1125,9 @@ static int __init dccp_init(void)
                 goto out_sysctl_exit;
 
         dccp_timestamping_init();
-out:
-        return rc;
+
+        return 0;
+
 out_sysctl_exit:
         dccp_sysctl_exit();
 out_ackvec_exit:
@@ -1135,18 +1136,19 @@ out_free_dccp_mib:
         dccp_mib_exit();
 out_free_dccp_bhash:
         free_pages((unsigned long)dccp_hashinfo.bhash, bhash_order);
-        dccp_hashinfo.bhash = NULL;
 out_free_dccp_locks:
         inet_ehash_locks_free(&dccp_hashinfo);
 out_free_dccp_ehash:
         free_pages((unsigned long)dccp_hashinfo.ehash, ehash_order);
-        dccp_hashinfo.ehash = NULL;
 out_free_bind_bucket_cachep:
         kmem_cache_destroy(dccp_hashinfo.bind_bucket_cachep);
-        dccp_hashinfo.bind_bucket_cachep = NULL;
 out_free_percpu:
         percpu_counter_destroy(&dccp_orphan_count);
-        goto out;
+out_fail:
+        dccp_hashinfo.bhash = NULL;
+        dccp_hashinfo.ehash = NULL;
+        dccp_hashinfo.bind_bucket_cachep = NULL;
+        return rc;
 }
 
 static void __exit dccp_fini(void)