From: Mike Christie michael.christie@oracle.com
[ Upstream commit 57569c37f0add1b6489e1a1563c71519daf732cf ]
Fix a NULL pointer crash that occurs when we are freeing the socket at the same time we access it via sysfs.
The problem is that:
1. iscsi_sw_tcp_conn_get_param() and iscsi_sw_tcp_host_get_param() take the frwd_lock and do sock_hold() then drop the frwd_lock. sock_hold() does a get on the "struct sock".
2. iscsi_sw_tcp_release_conn() does sockfd_put() which does the last put on the "struct socket" and that does __sock_release() which sets the sock->ops to NULL.
3. iscsi_sw_tcp_conn_get_param() and iscsi_sw_tcp_host_get_param() then call kernel_getpeername() which accesses the NULL sock->ops.
Above we do a get on the "struct sock", but we needed a get on the "struct socket". Originally, we just held the frwd_lock the entire time but in commit bcf3a2953d36 ("scsi: iscsi: iscsi_tcp: Avoid holding spinlock while calling getpeername()") we switched to refcount based because the network layer changed and started taking a mutex in that path, so we could no longer hold the frwd_lock.
Instead of trying to maintain multiple refcounts, this just has us use a mutex for accessing the socket in the interface code paths.
Link: https://lore.kernel.org/r/20220907221700.10302-1-michael.christie@oracle.com Fixes: bcf3a2953d36 ("scsi: iscsi: iscsi_tcp: Avoid holding spinlock while calling getpeername()") Signed-off-by: Mike Christie michael.christie@oracle.com Signed-off-by: Martin K. Petersen martin.petersen@oracle.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/scsi/iscsi_tcp.c | 73 ++++++++++++++++++++++++++++------------ drivers/scsi/iscsi_tcp.h | 2 ++ 2 files changed, 54 insertions(+), 21 deletions(-)
diff --git a/drivers/scsi/iscsi_tcp.c b/drivers/scsi/iscsi_tcp.c index df47557a02a3..6485c1aa9e74 100644 --- a/drivers/scsi/iscsi_tcp.c +++ b/drivers/scsi/iscsi_tcp.c @@ -558,6 +558,8 @@ iscsi_sw_tcp_conn_create(struct iscsi_cls_session *cls_session, tcp_conn = conn->dd_data; tcp_sw_conn = tcp_conn->dd_data;
+ mutex_init(&tcp_sw_conn->sock_lock); + tfm = crypto_alloc_ahash("crc32c", 0, CRYPTO_ALG_ASYNC); if (IS_ERR(tfm)) goto free_conn; @@ -592,11 +594,15 @@ iscsi_sw_tcp_conn_create(struct iscsi_cls_session *cls_session,
static void iscsi_sw_tcp_release_conn(struct iscsi_conn *conn) { - struct iscsi_session *session = conn->session; struct iscsi_tcp_conn *tcp_conn = conn->dd_data; struct iscsi_sw_tcp_conn *tcp_sw_conn = tcp_conn->dd_data; struct socket *sock = tcp_sw_conn->sock;
+ /* + * The iscsi transport class will make sure we are not called in + * parallel with start, stop, bind and destroys. However, this can be + * called twice if userspace does a stop then a destroy. + */ if (!sock) return;
@@ -604,9 +610,9 @@ static void iscsi_sw_tcp_release_conn(struct iscsi_conn *conn) iscsi_sw_tcp_conn_restore_callbacks(conn); sock_put(sock->sk);
- spin_lock_bh(&session->frwd_lock); + mutex_lock(&tcp_sw_conn->sock_lock); tcp_sw_conn->sock = NULL; - spin_unlock_bh(&session->frwd_lock); + mutex_unlock(&tcp_sw_conn->sock_lock); sockfd_put(sock); }
@@ -658,7 +664,6 @@ iscsi_sw_tcp_conn_bind(struct iscsi_cls_session *cls_session, struct iscsi_cls_conn *cls_conn, uint64_t transport_eph, int is_leading) { - struct iscsi_session *session = cls_session->dd_data; struct iscsi_conn *conn = cls_conn->dd_data; struct iscsi_tcp_conn *tcp_conn = conn->dd_data; struct iscsi_sw_tcp_conn *tcp_sw_conn = tcp_conn->dd_data; @@ -678,10 +683,10 @@ iscsi_sw_tcp_conn_bind(struct iscsi_cls_session *cls_session, if (err) goto free_socket;
- spin_lock_bh(&session->frwd_lock); + mutex_lock(&tcp_sw_conn->sock_lock); /* bind iSCSI connection and socket */ tcp_sw_conn->sock = sock; - spin_unlock_bh(&session->frwd_lock); + mutex_unlock(&tcp_sw_conn->sock_lock);
/* setup Socket parameters */ sk = sock->sk; @@ -717,8 +722,15 @@ static int iscsi_sw_tcp_conn_set_param(struct iscsi_cls_conn *cls_conn, break; case ISCSI_PARAM_DATADGST_EN: iscsi_set_param(cls_conn, param, buf, buflen); + + mutex_lock(&tcp_sw_conn->sock_lock); + if (!tcp_sw_conn->sock) { + mutex_unlock(&tcp_sw_conn->sock_lock); + return -ENOTCONN; + } tcp_sw_conn->sendpage = conn->datadgst_en ? sock_no_sendpage : tcp_sw_conn->sock->ops->sendpage; + mutex_unlock(&tcp_sw_conn->sock_lock); break; case ISCSI_PARAM_MAX_R2T: return iscsi_tcp_set_max_r2t(conn, buf); @@ -733,8 +745,8 @@ static int iscsi_sw_tcp_conn_get_param(struct iscsi_cls_conn *cls_conn, enum iscsi_param param, char *buf) { struct iscsi_conn *conn = cls_conn->dd_data; - struct iscsi_tcp_conn *tcp_conn = conn->dd_data; - struct iscsi_sw_tcp_conn *tcp_sw_conn = tcp_conn->dd_data; + struct iscsi_sw_tcp_conn *tcp_sw_conn; + struct iscsi_tcp_conn *tcp_conn; struct sockaddr_in6 addr; struct socket *sock; int rc; @@ -744,21 +756,36 @@ static int iscsi_sw_tcp_conn_get_param(struct iscsi_cls_conn *cls_conn, case ISCSI_PARAM_CONN_ADDRESS: case ISCSI_PARAM_LOCAL_PORT: spin_lock_bh(&conn->session->frwd_lock); - if (!tcp_sw_conn || !tcp_sw_conn->sock) { + if (!conn->session->leadconn) { spin_unlock_bh(&conn->session->frwd_lock); return -ENOTCONN; } - sock = tcp_sw_conn->sock; - sock_hold(sock->sk); + /* + * The conn has been setup and bound, so just grab a ref + * incase a destroy runs while we are in the net layer. + */ + iscsi_get_conn(conn->cls_conn); spin_unlock_bh(&conn->session->frwd_lock);
+ tcp_conn = conn->dd_data; + tcp_sw_conn = tcp_conn->dd_data; + + mutex_lock(&tcp_sw_conn->sock_lock); + sock = tcp_sw_conn->sock; + if (!sock) { + rc = -ENOTCONN; + goto sock_unlock; + } + if (param == ISCSI_PARAM_LOCAL_PORT) rc = kernel_getsockname(sock, (struct sockaddr *)&addr); else rc = kernel_getpeername(sock, (struct sockaddr *)&addr); - sock_put(sock->sk); +sock_unlock: + mutex_unlock(&tcp_sw_conn->sock_lock); + iscsi_put_conn(conn->cls_conn); if (rc < 0) return rc;
@@ -796,17 +823,21 @@ static int iscsi_sw_tcp_host_get_param(struct Scsi_Host *shost, } tcp_conn = conn->dd_data; tcp_sw_conn = tcp_conn->dd_data; - sock = tcp_sw_conn->sock; - if (!sock) { - spin_unlock_bh(&session->frwd_lock); - return -ENOTCONN; - } - sock_hold(sock->sk); + /* + * The conn has been setup and bound, so just grab a ref + * incase a destroy runs while we are in the net layer. + */ + iscsi_get_conn(conn->cls_conn); spin_unlock_bh(&session->frwd_lock);
- rc = kernel_getsockname(sock, - (struct sockaddr *)&addr); - sock_put(sock->sk); + mutex_lock(&tcp_sw_conn->sock_lock); + sock = tcp_sw_conn->sock; + if (!sock) + rc = -ENOTCONN; + else + rc = kernel_getsockname(sock, (struct sockaddr *)&addr); + mutex_unlock(&tcp_sw_conn->sock_lock); + iscsi_put_conn(conn->cls_conn); if (rc < 0) return rc;
diff --git a/drivers/scsi/iscsi_tcp.h b/drivers/scsi/iscsi_tcp.h index 791453195099..1731956326e2 100644 --- a/drivers/scsi/iscsi_tcp.h +++ b/drivers/scsi/iscsi_tcp.h @@ -28,6 +28,8 @@ struct iscsi_sw_tcp_send {
struct iscsi_sw_tcp_conn { struct socket *sock; + /* Taken when accessing the sock from the netlink/sysfs interface */ + struct mutex sock_lock;
struct iscsi_sw_tcp_send out; /* old values for socket callbacks */