From eca5cd9474cd26d62f9756f536e2e656d3f62f3a Mon Sep 17 00:00:00 2001

From: Saravanan Vajravel <saravanan.vajravel@broadcom.com>

Date: Wed, 5 Apr 2023 21:25:49 -0700

Subject: [PATCH 1/1] RDMA/srpt: Add a check for valid 'mad_agent' pointer

Git-commit: eca5cd9474cd26d62f9756f536e2e656d3f62f3a

Patch-mainline: v6.4-rc1

References: git-fixes

When unregistering MAD agent, srpt module has a non-null check

for 'mad_agent' pointer before invoking ib_unregister_mad_agent().

This check can pass if 'mad_agent' variable holds an error value.

The 'mad_agent' can have an error value for a short window when

srpt_add_one() and srpt_remove_one() is executed simultaneously.

In srpt module, added a valid pointer check for 'sport->mad_agent'

before unregistering MAD agent.

This issue can hit when RoCE driver unregisters ib_device

Stack Trace:

------------

BUG: kernel NULL pointer dereference, address: 000000000000004d

PGD 145003067 P4D 145003067 PUD 2324fe067 PMD 0

Oops: 0002 [#1] PREEMPT SMP NOPTI

CPU: 10 PID: 4459 Comm: kworker/u80:0 Kdump: loaded Tainted: P

Hardware name: Dell Inc. PowerEdge R640/06NR82, BIOS 2.5.4 01/13/2020

Workqueue: bnxt_re bnxt_re_task [bnxt_re]

RIP: 0010:_raw_spin_lock_irqsave+0x19/0x40

Call Trace:

  ib_unregister_mad_agent+0x46/0x2f0 [ib_core]

  IPv6: ADDRCONF(NETDEV_CHANGE): bond0: link becomes ready

  ? __schedule+0x20b/0x560

  srpt_unregister_mad_agent+0x93/0xd0 [ib_srpt]

  srpt_remove_one+0x20/0x150 [ib_srpt]

  remove_client_context+0x88/0xd0 [ib_core]

  bond0: (slave p2p1): link status definitely up, 100000 Mbps full duplex

  disable_device+0x8a/0x160 [ib_core]

  bond0: active interface up!

  ? kernfs_name_hash+0x12/0x80

 (NULL device *): Bonding Info Received: rdev: 000000006c0b8247

  __ib_unregister_device+0x42/0xb0 [ib_core]

 (NULL device *):         Master: mode: 4 num_slaves:2

  ib_unregister_device+0x22/0x30 [ib_core]

 (NULL device *):         Slave: id: 105069936 name:p2p1 link:0 state:0

  bnxt_re_stopqps_and_ib_uninit+0x83/0x90 [bnxt_re]

  bnxt_re_alloc_lag+0x12e/0x4e0 [bnxt_re]

Fixes: a42d985bd5b2 ("ib_srpt: Initial SRP Target merge for v3.3-rc1")

Reviewed-by: Selvin Xavier <selvin.xavier@broadcom.com>

Reviewed-by: Kashyap Desai <kashyap.desai@broadcom.com>

Signed-off-by: Saravanan Vajravel <saravanan.vajravel@broadcom.com>

Link: https://lore.kernel.org/r/20230406042549.507328-1-saravanan.vajravel@broadcom.com

Reviewed-by: Bart Van Assche <bvanassche@acm.org>

Signed-off-by: Leon Romanovsky <leon@kernel.org>

Acked-by: Nicolas Morey <nmorey@suse.com>

---

 drivers/infiniband/ulp/srpt/ib_srpt.c | 23 +++++++++++++----------

 1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/drivers/infiniband/ulp/srpt/ib_srpt.c b/drivers/infiniband/ulp/srpt/ib_srpt.c

index 3c3fae738c3e..25e799dba999 100644

--- a/drivers/infiniband/ulp/srpt/ib_srpt.c

+++ b/drivers/infiniband/ulp/srpt/ib_srpt.c

@@ -549,6 +549,7 @@ static int srpt_format_guid(char *buf, unsigned int size, const __be64 *guid)

  */

 static int srpt_refresh_port(struct srpt_port *sport)

 {

+	struct ib_mad_agent *mad_agent;

 	struct ib_mad_reg_req reg_req;

 	struct ib_port_modify port_modify;

 	struct ib_port_attr port_attr;

@@ -593,24 +594,26 @@ static int srpt_refresh_port(struct srpt_port *sport)

 		set_bit(IB_MGMT_METHOD_GET, reg_req.method_mask);

 		set_bit(IB_MGMT_METHOD_SET, reg_req.method_mask);

-		sport->mad_agent = ib_register_mad_agent(sport->sdev->device,

-							 sport->port,

-							 IB_QPT_GSI,

-							 &reg_req, 0,

-							 srpt_mad_send_handler,

-							 srpt_mad_recv_handler,

-							 sport, 0);

-		if (IS_ERR(sport->mad_agent)) {

+		mad_agent = ib_register_mad_agent(sport->sdev->device,

+						  sport->port,

+						  IB_QPT_GSI,

+						  &reg_req, 0,

+						  srpt_mad_send_handler,

+						  srpt_mad_recv_handler,

+						  sport, 0);

+		if (IS_ERR(mad_agent)) {

 			pr_err("%s-%d: MAD agent registration failed (%ld). Note: this is expected if SR-IOV is enabled.\n",

 			       dev_name(&sport->sdev->device->dev), sport->port,

-			       PTR_ERR(sport->mad_agent));

+			       PTR_ERR(mad_agent));

 			sport->mad_agent = NULL;

 			memset(&port_modify, 0, sizeof(port_modify));

 			port_modify.clr_port_cap_mask = IB_PORT_DEVICE_MGMT_SUP;

 			ib_modify_port(sport->sdev->device, sport->port, 0,

 				       &port_modify);

-

+			return 0;

 		}

+

+		sport->mad_agent = mad_agent;

 	}

 	return 0;

-- 

2.39.1.1.gbe015eda0162