[PATCH AUTOSEL 5.4 316/330] scsi: libfc: Handling of extra kref

Sasha Levin
2020-09-18T02:54:08Z

From: Javed Hasan <jhasan@marvell.com>

[ Upstream commit 71f2bf85e90d938d4a9ef9dd9bfa8d9b0b6a03f7 ]

Handling of extra kref which is done by lookup table in case rdata is
already present in list.

This issue was leading to memory leak. Trace from KMEMLEAK tool:

unreferenced object 0xffff8888259e8780 (size 512):
comm "kworker/2:1", pid 182614, jiffies 4433237386 (age 113021.971s)
hex dump (first 32 bytes):
58 0a ec cf 83 88 ff ff 00 00 00 00 00 00 00 00
01 00 00 00 08 00 00 00 13 7d f0 1e 0e 00 00 10
backtrace:
[<000000006b25760f>] fc_rport_recv_req+0x3c6/0x18f0 [libfc]
[<00000000f208d994>] fc_lport_recv_els_req+0x120/0x8a0 [libfc]
[<00000000a9c437b8>] fc_lport_recv+0xb9/0x130 [libfc]
[<00000000ad5be37b>] qedf_ll2_process_skb+0x73d/0xad0 [qedf]
[<00000000e0eb6893>] process_one_work+0x382/0x6c0
[<000000002dfd9e21>] worker_thread+0x57/0x5c0
[<00000000b648204f>] kthread+0x1a0/0x1c0
[<0000000072f5ab20>] ret_from_fork+0x35/0x40
[<000000001d5c05d8>] 0xffffffffffffffff

Below is the log sequence which leads to memory leak. Here we get the
nested "Received PLOGI request" for same port and this request leads to
call the fc_rport_create() twice for the same rport.

kernel: host1: rport fffce5: Received PLOGI request
kernel: host1: rport fffce5: Received PLOGI in INIT state
kernel: host1: rport fffce5: Port is Ready
kernel: host1: rport fffce5: Received PRLI request while in state Ready
kernel: host1: rport fffce5: PRLI rspp type 8 active 1 passive 0
kernel: host1: rport fffce5: Received LOGO request while in state Ready
kernel: host1: rport fffce5: Delete port
kernel: host1: rport fffce5: Received PLOGI request
kernel: host1: rport fffce5: Received PLOGI in state Delete - send busy

Link: https://lore.kernel.org/r/20200622101212.3922-2-jhasan@marvell.com
Reviewed-by: Girish Basrur <gbasrur@marvell.com>
Reviewed-by: Saurav Kashyap <skashyap@marvell.com>
Reviewed-by: Shyam Sundar <ssundar@marvell.com>
Signed-off-by: Javed Hasan <jhasan@marvell.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/scsi/libfc/fc_rport.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/libfc/fc_rport.c b/drivers/scsi/libfc/fc_rport.c
index 6bb8917b99a19..aabf51df3c02f 100644
--- a/drivers/scsi/libfc/fc_rport.c
+++ b/drivers/scsi/libfc/fc_rport.c
@@ -133,8 +133,10 @@ struct fc_rport_priv *fc_rport_create(struct fc_lport *lport, u32 port_id)
lockdep_assert_held(&lport->disc.disc_mutex);

rdata = fc_rport_lookup(lport, port_id);
- if (rdata)
+ if (rdata) {
+ kref_put(&rdata->kref, fc_rport_destroy);
return rdata;
+ }

if (lport->rport_priv_size > 0)
rport_priv_size = lport->rport_priv_size;
--
2.25.1