[PATCH AUTOSEL 5.3 27/33] RDMA/siw: Fix serialization issue in write_space()

Sasha Levin
2019-10-25T14:06:22Z

From: Krishnamraju Eraparaju <krishna2@chelsio.com>

[ Upstream commit df791c54d627bae53c9be3be40a69594c55de487 ]

In siw_qp_llp_write_space(), 'sock' members should be accessed with
sk_callback_lock held, otherwise, it could race with
siw_sk_restore_upcalls(). And this could cause "NULL deref" panic. Below
panic is due to the NULL cep returned from sk_to_cep(sk):

Call Trace:
<IRQ> siw_qp_llp_write_space+0x11/0x40 [siw]
tcp_check_space+0x4c/0xf0
tcp_rcv_established+0x52b/0x630
tcp_v4_do_rcv+0xf4/0x1e0
tcp_v4_rcv+0x9b8/0xab0
ip_protocol_deliver_rcu+0x2c/0x1c0
ip_local_deliver_finish+0x44/0x50
ip_local_deliver+0x6b/0xf0
? ip_protocol_deliver_rcu+0x1c0/0x1c0
ip_rcv+0x52/0xd0
? ip_rcv_finish_core.isra.14+0x390/0x390
__netif_receive_skb_one_core+0x83/0xa0
netif_receive_skb_internal+0x73/0xb0
napi_gro_frags+0x1ff/0x2b0
t4_ethrx_handler+0x4a7/0x740 [cxgb4]
process_responses+0x2c9/0x590 [cxgb4]
? t4_sge_intr_msix+0x1d/0x30 [cxgb4]
? handle_irq_event_percpu+0x51/0x70
? handle_irq_event+0x41/0x60
? handle_edge_irq+0x97/0x1a0
napi_rx_handler+0x14/0xe0 [cxgb4]
net_rx_action+0x2af/0x410
__do_softirq+0xda/0x2a8
do_softirq_own_stack+0x2a/0x40
</IRQ>
do_softirq+0x50/0x60
__local_bh_enable_ip+0x50/0x60
ip_finish_output2+0x18f/0x520
ip_output+0x6e/0xf0
? __ip_finish_output+0x1f0/0x1f0
__ip_queue_xmit+0x14f/0x3d0
? __slab_alloc+0x4b/0x58
__tcp_transmit_skb+0x57d/0xa60
tcp_write_xmit+0x23b/0xfd0
__tcp_push_pending_frames+0x2e/0xf0
tcp_sendmsg_locked+0x939/0xd50
tcp_sendmsg+0x27/0x40
sock_sendmsg+0x57/0x80
siw_tx_hdt+0x894/0xb20 [siw]
? find_busiest_group+0x3e/0x5b0
? common_interrupt+0xa/0xf
? common_interrupt+0xa/0xf
? common_interrupt+0xa/0xf
siw_qp_sq_process+0xf1/0xe60 [siw]
? __wake_up_common_lock+0x87/0xc0
siw_sq_resume+0x33/0xe0 [siw]
siw_run_sq+0xac/0x190 [siw]
? remove_wait_queue+0x60/0x60
kthread+0xf8/0x130
? siw_sq_resume+0xe0/0xe0 [siw]
? kthread_bind+0x10/0x10
ret_from_fork+0x35/0x40

Fixes: f29dd55b0236 ("rdma/siw: queue pair methods")
Link: https://lore.kernel.org/r/20190923101112.32685-1-krishna2@chelsio.com
Signed-off-by: Krishnamraju Eraparaju <krishna2@chelsio.com>
Reviewed-by: Bernard Metzler <bmt@zurich.ibm.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/infiniband/sw/siw/siw_qp.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/infiniband/sw/siw/siw_qp.c b/drivers/infiniband/sw/siw/siw_qp.c
index 430314c8abd94..52d402f39df93 100644
--- a/drivers/infiniband/sw/siw/siw_qp.c
+++ b/drivers/infiniband/sw/siw/siw_qp.c
@@ -182,12 +182,19 @@ void siw_qp_llp_close(struct siw_qp *qp)
*/
void siw_qp_llp_write_space(struct sock *sk)
{
- struct siw_cep *cep = sk_to_cep(sk);
+ struct siw_cep *cep;

- cep->sk_write_space(sk);
+ read_lock(&sk->sk_callback_lock);
+
+ cep = sk_to_cep(sk);
+ if (cep) {
+ cep->sk_write_space(sk);

- if (!test_bit(SOCK_NOSPACE, &sk->sk_socket->flags))
- (void)siw_sq_start(cep->qp);
+ if (!test_bit(SOCK_NOSPACE, &sk->sk_socket->flags))
+ (void)siw_sq_start(cep->qp);
+ }
+
+ read_unlock(&sk->sk_callback_lock);
}

static int siw_qp_readq_init(struct siw_qp *qp, int irq_size, int orq_size)
--
2.20.1