kernel: net: rds: CVE-2015-7990

Fixes Race condition when sending message on unbound socket causing NULL
pointer dereference.

CVE-2015-7990 is a complete fix for CVE-2015-6937.

References:
https://lkml.org/lkml/2015/10/16/530
https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2015-7990

Signed-off-by: Sona Sarmadi <sona.sarmadi@enea.com>
Signed-off-by: Tudor Florea <tudor.florea@enea.com>

1 files changed, 80 insertions, 0 deletions

diff --git a/recipes-kernel/linux/linux-hierofalcon/RDS-CVE-2015-7990-a-complete-fix-of-CVE-2015-6937.patch b/recipes-kernel/linux/linux-hierofalcon/RDS-CVE-2015-7990-a-complete-fix-of-CVE-2015-6937.patch
new file mode 100644
index 0000000..c73d743
--- /dev/null
+++ b/recipes-kernel/linux/linux-hierofalcon/RDS-CVE-2015-7990-a-complete-fix-of-CVE-2015-6937.patch
@@ -0,0 +1,80 @@
+From    Quentin Casasnovas <>
+Subject [PATCH] RDS: fix race condition when sending a message on unbound
+socket.
+Date    Fri, 16 Oct 2015 17:11:42 +0200
+        
+
+Sasha's found a NULL pointer dereference in the RDS connection code when
+sending a message to an apparently unbound socket.  The problem is caused
+by the code checking if the socket is bound in rds_sendmsg(), which checks
+the rs_bound_addr field without taking a lock on the socket.  This opens a
+race where rs_bound_addr is temporarily set but where the transport is not
+in rds_bind(), leading to a NULL pointer dereference when trying to
+dereference 'trans' in __rds_conn_create().
+
+Vegard wrote a reproducer for this issue, so kindly ask him to share if
+you're interested.
+
+I cannot reproduce the NULL pointer dereference using Vegard's reproducer
+with this patch, whereas I could without.
+
+Complete earlier incomplete fix to CVE-2015-6937:
+
+  74e98eb08588 ("RDS: verify the underlying transport exists before creating a
+connection")
+
+Fix for CVE-2015-7990, [from https://lkml.org/lkml/2015/10/16/530]
+
+Upstream-Status: Submitted
+
+Signed-off-by: Quentin Casasnovas <quentin.casasnovas@oracle.com>
+Reviewed-by: Vegard Nossum <vegard.nossum@oracle.com>
+Reviewed-by: Sasha Levin <sasha.levin@oracle.com>
+Cc: Vegard Nossum <vegard.nossum@oracle.com>
+Cc: Sasha Levin <sasha.levin@oracle.com>
+Cc: Chien Yen <chien.yen@oracle.com>
+Cc: Santosh Shilimkar <santosh.shilimkar@oracle.com>
+Cc: David S. Miller <davem@davemloft.net>
+Cc: stable@vger.kernel.org
+---
+ net/rds/connection.c | 6 ------
+ net/rds/send.c       | 4 +++-
+ 2 files changed, 3 insertions(+), 7 deletions(-)
+diff --git a/net/rds/connection.c b/net/rds/connection.c
+index 49adeef..9b2de5e 100644
+--- a/net/rds/connection.c
++++ b/net/rds/connection.c
+@@ -190,12 +190,6 @@ new_conn:
+                }
+        }
+
+-       if (trans == NULL) {
+-               kmem_cache_free(rds_conn_slab, conn);
+-               conn = ERR_PTR(-ENODEV);
+-               goto out;
+-       }
+-
+        conn->c_trans = trans;
+
+        ret = trans->conn_alloc(conn, gfp);
+diff --git a/net/rds/send.c b/net/rds/send.c
+index 4df61a5..859de6f 100644
+--- a/net/rds/send.c
++++ b/net/rds/send.c
+@@ -1009,11 +1009,13 @@ int rds_sendmsg(struct socket *sock, struct msghdr *msg, size_t payload_len)
+                release_sock(sk);
+        }
+
+-       /* racing with another thread binding seems ok here */
++       lock_sock(sk);
+        if (daddr == 0 || rs->rs_bound_addr == 0) {
++               release_sock(sk);
+                ret = -ENOTCONN; /* XXX not a great errno */
+                goto out;
+        }
++       release_sock(sk);
+
+        if (payload_len > rds_sk_sndbuf(rs)) {
+                ret = -EMSGSIZE;
+--
+2.4.9