diff options
| author | Quentin Casasnovas | 2015-11-24 17:13:21 -0500 |
|---|---|---|
| committer | David S. Miller | 2015-11-24 17:20:09 -0500 |
| commit | 8c7188b23474cca017b3ef354c4a58456f68303a (patch) | |
| tree | ccc6f99c22d92ce0ec5c91076ee7acaf2fab01ff | |
| parent | 20f795666d3accbb75969730019aeb03f50ef0ec (diff) | |
RDS: fix race condition when sending a message on unbound socket
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")
Cc: David S. Miller <davem@davemloft.net>
Cc: stable@vger.kernel.org
Reviewed-by: Vegard Nossum <vegard.nossum@oracle.com>
Reviewed-by: Sasha Levin <sasha.levin@oracle.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | net/rds/connection.c | 6 | ||||
| -rw-r--r-- | 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 d4564036a339..e3b118cae81d 100644 --- a/net/rds/connection.c +++ b/net/rds/connection.c @@ -186,12 +186,6 @@ static struct rds_connection *__rds_conn_create(struct net *net, } } - 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 827155c2ead1..c9cdb358ea88 100644 --- a/net/rds/send.c +++ b/net/rds/send.c @@ -1013,11 +1013,13 @@ 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; |