diff options
| author | Quentin Casasnovas <quentin.casasnovas@oracle.com> | 2015-11-24 17:13:21 -0500 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2015-12-30 02:25:58 +0000 |
| commit | 6240b18899c2ff1bfe29a1475a527f4e10662cb0 (patch) | |
| tree | 0dd014ce30786b7ab1ee9282ef28a5949d9c5d96 | |
| parent | 062d75332dfb0a31d97c702b2cf31cc0705cdb3b (diff) | |
| download | linux-6240b18899c2ff1bfe29a1475a527f4e10662cb0.tar.gz linux-6240b18899c2ff1bfe29a1475a527f4e10662cb0.tar.bz2 linux-6240b18899c2ff1bfe29a1475a527f4e10662cb0.zip | |
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>
| -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 be3eecdebcc4..9e07c756d1f9 100644 --- a/net/rds/connection.c +++ b/net/rds/connection.c @@ -178,12 +178,6 @@ 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 88eace57dd6b..31c9fa464b11 100644 --- a/net/rds/send.c +++ b/net/rds/send.c @@ -955,11 +955,13 @@ 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); /* size of rm including all sgs */ ret = rds_rm_size(msg, payload_len); |