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authorQuentin Casasnovas <quentin.casasnovas@oracle.com>2015-11-24 17:13:21 -0500
committerSasha Levin <sasha.levin@oracle.com>2016-01-21 11:23:27 -0500
commit96c7b10cd8000973035b667adf62ea1164f4b9b4 (patch)
treeec5136b73a01d39c8a1b1ca905e87c80d0a8221b
parent72032798034d921ed565e3bf8dfdc3098f6473e2 (diff)
downloadlwn-96c7b10cd8000973035b667adf62ea1164f4b9b4.tar.gz
lwn-96c7b10cd8000973035b667adf62ea1164f4b9b4.zip
RDS: fix race condition when sending a message on unbound socket
[ Upstream commit 8c7188b23474cca017b3ef354c4a58456f68303a ] 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> Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
-rw-r--r--net/rds/connection.c6
-rw-r--r--net/rds/send.c4
2 files changed, 3 insertions, 7 deletions
diff --git a/net/rds/connection.c b/net/rds/connection.c
index f5fb7d6b7c41..378c3a6acf84 100644
--- a/net/rds/connection.c
+++ b/net/rds/connection.c
@@ -183,12 +183,6 @@ 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 0a64541020b0..0bae8d43b012 100644
--- a/net/rds/send.c
+++ b/net/rds/send.c
@@ -958,11 +958,13 @@ 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);