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| author | Quentin Casasnovas <quentin.casasnovas@oracle.com> | 2015-11-24 17:13:21 -0500 |
|---|---|---|
| committer | Willy Tarreau <w@1wt.eu> | 2016-01-29 22:12:39 +0100 |
| commit | 31fefb1f987a7958f75bb19c296807e53d9f3644 (patch) | |
| tree | 7e95b4c43adabb22ed0d5921f474467297fb6981 | |
| parent | 42fc512469e78939c1e419d3310c47de55bdcbb8 (diff) | |
| download | for-greg-31fefb1f987a7958f75bb19c296807e53d9f3644.tar.gz | |
RDS: fix race condition when sending a message on unbound socket
commit 8c7188b23474cca017b3ef354c4a58456f68303a upstream.
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>
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>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Willy Tarreau <w@1wt.eu>
| -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 8c3ddcdcab9328..cc8b568c0c8422 100644 --- a/net/rds/connection.c +++ b/net/rds/connection.c @@ -187,12 +187,6 @@ static struct rds_connection *__rds_conn_create(__be32 laddr, __be32 faddr, } } - 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 28c88ff3d038a0..ad1a2d8314c945 100644 --- a/net/rds/send.c +++ b/net/rds/send.c @@ -842,11 +842,13 @@ int rds_sendmsg(struct kiocb *iocb, struct socket *sock, struct msghdr *msg, 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); rm = rds_message_copy_from_user(msg->msg_iov, payload_len); if (IS_ERR(rm)) { |