[PATCH 4/7] IB/srp: Avoid a cable pull can trigger a kernel crash

[PATCH 4/7] IB/srp: Avoid a cable pull can trigger a kernel crash

[Bart Van Assche]

This patch fixes the following kernel crash:

general protection fault: 0000 [#1] PREEMPT SMP
Workqueue: ib_mad2 timeout_sends [ib_core]
Call Trace:
 ib_sa_path_rec_callback+0x1c4/0x1d0 [ib_core]
 send_handler+0xb2/0xd0 [ib_core]
 timeout_sends+0x14d/0x220 [ib_core]
 process_one_work+0x200/0x630
 worker_thread+0x4e/0x3b0
 kthread+0x113/0x150

Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: <stable@vger.kernel.org>
---
 drivers/infiniband/ulp/srp/ib_srp.c | 25 +++++++++++++++++++------
 1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c
index 778a08250f16..8ceb4bb011f1 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.c
+++ b/drivers/infiniband/ulp/srp/ib_srp.c
@@ -665,12 +665,19 @@ static void srp_path_rec_completion(int status,
 static int srp_lookup_path(struct srp_rdma_ch *ch)
 {
 	struct srp_target_port *target = ch->target;
-	int ret;
+	int ret = -ENODEV;
 
 	ch->path.numb_path = 1;
 
 	init_completion(&ch->done);
 
+	/*
+	 * Avoid that the SCSI host can be removed by srp_remove_target()
+	 * before srp_path_rec_completion() is called.
+	 */
+	if (!scsi_host_get(target->scsi_host))
+		goto out;
+
 	ch->path_query_id = ib_sa_path_rec_get(&srp_sa_client,
 					       target->srp_host->srp_dev->dev,
 					       target->srp_host->port,
@@ -684,18 +691,24 @@ static int srp_lookup_path(struct srp_rdma_ch *ch)
 					       GFP_KERNEL,
 					       srp_path_rec_completion,
 					       ch, &ch->path_query);
-	if (ch->path_query_id < 0)
-		return ch->path_query_id;
+	ret = ch->path_query_id;
+	if (ret < 0)
+		goto put;
 
 	ret = wait_for_completion_interruptible(&ch->done);
 	if (ret < 0)
-		return ret;
+		goto put;
 
-	if (ch->status < 0)
+	ret = ch->status;
+	if (ret < 0)
 		shost_printk(KERN_WARNING, target->scsi_host,
 			     PFX "Path record query failed\n");
 
-	return ch->status;
+put:
+	scsi_host_put(target->scsi_host);
+
+out:
+	return ret;
 }
 
 static int srp_send_req(struct srp_rdma_ch *ch, bool multich)
-- 
2.14.2

Re: [PATCH 4/7] IB/srp: Avoid a cable pull can trigger a kernel crash

[Leon Romanovsky]

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On Fri, Oct 06, 2017 at 02:42:40PM -0700, Bart Van Assche wrote:
> This patch fixes the following kernel crash:
>
> general protection fault: 0000 [#1] PREEMPT SMP
> Workqueue: ib_mad2 timeout_sends [ib_core]
> Call Trace:
>  ib_sa_path_rec_callback+0x1c4/0x1d0 [ib_core]
>  send_handler+0xb2/0xd0 [ib_core]
>  timeout_sends+0x14d/0x220 [ib_core]
>  process_one_work+0x200/0x630
>  worker_thread+0x4e/0x3b0
>  kthread+0x113/0x150
>
> Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
> Cc: <stable@vger.kernel.org>

You need Fixes tag for the stable tree.

Thanks

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Re: [PATCH 4/7] IB/srp: Avoid a cable pull can trigger a kernel crash

[Bart Van Assche]

On Sun, 2017-10-08 at 16:22 +0300, Leon Romanovsky wrote:
> On Fri, Oct 06, 2017 at 02:42:40PM -0700, Bart Van Assche wrote:
> > This patch fixes the following kernel crash:
> > 
> > general protection fault: 0000 [#1] PREEMPT SMP
> > Workqueue: ib_mad2 timeout_sends [ib_core]
> > Call Trace:
> >  ib_sa_path_rec_callback+0x1c4/0x1d0 [ib_core]
> >  send_handler+0xb2/0xd0 [ib_core]
> >  timeout_sends+0x14d/0x220 [ib_core]
> >  process_one_work+0x200/0x630
> >  worker_thread+0x4e/0x3b0
> >  kthread+0x113/0x150
> > 
> > Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
> > Cc: <stable@vger.kernel.org>
> 
> You need Fixes tag for the stable tree.

Hello Leon,

OK, I will add that tag when I repost this patch series.

Bart.

Re: [PATCH 4/7] IB/srp: Avoid a cable pull can trigger a kernel crash

[Sagi Grimberg]

Looks good,

Reviewed-by: Sagi Grimberg <sagi@grimberg.me>