Re: [PATCH] RDMA/srp: fix use-after-free of a request in srp_destroy_qp()

[Bart Van Assche]

On 8/12/26 12:04 PM, Yehyeong Lee wrote:
> srp_destroy_qp() drains the send queue before destroying the queue pair.
> For the fast registration and invalidation work requests, the wr_cqe it
> finds there is &req->reg_cqe, which lives in the blk-mq request pool.
> srp_remove_target() frees that pool first, through scsi_remove_host():
> page_owner records the page freed by blk_mq_free_tags_callback() while
> that call is running.  __ib_process_cq() then calls wc->wr_cqe->done on
> it.

Can this crash also be fixed by modifying srp_remove_target() as shown
below?

Thanks,

Bart.


From: Bart Van Assche <bvanassche@xxxxxxx>
Date: Fri, 14 Aug 2026 17:00:55 +0000
Subject: [PATCH] RDMA/srp: Fix srp_remove_target()

Remove all logical units before disconnecting the transport because one or
more SCSI commands may be submitted while removing logical units. Remove
the SCSI host after the transport has been disconnected because the code
that disconnects the transport needs resources that are freed by the code
that removes the SCSI host (SCSI host tag set). Remove the srp_rport_get()
and srp_rport_put() calls because the purpose of these calls was to keep
the rport until tl_err_work is cancelled.

Reported-by: Yehyeong Lee <yhlee@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx>
---
 drivers/infiniband/ulp/srp/ib_srp.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/infiniband/ulp/srp/ib_srp.c 
b/drivers/infiniband/ulp/srp/ib_srp.c
index acbd787de265..0b296b5715a8 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.c
+++ b/drivers/infiniband/ulp/srp/ib_srp.c
@@ -1038,15 +1038,20 @@ static void srp_del_scsi_host_attr(struct 
Scsi_Host *shost)

 static void srp_remove_target(struct srp_target_port *target)
 {
+	struct scsi_device *sdev;
 	struct srp_rdma_ch *ch;
 	int i;

 	WARN_ON_ONCE(target->state != SRP_TARGET_REMOVED);

 	srp_del_scsi_host_attr(target->scsi_host);
-	srp_rport_get(target->rport);
-	srp_remove_host(target->scsi_host);
-	scsi_remove_host(target->scsi_host);
+	/*
+	 * Remove all logical units. This must happen before the
+	 * srp_disconnect_target() call because scsi_remove_device() may trigger
+	 * submission of SCSI commands. See also sd_shutdown().
+	 */
+	shost_for_each_device(sdev, target->scsi_host)
+		scsi_remove_device(sdev);
 	srp_stop_rport_timers(target->rport);
 	srp_disconnect_target(target);
 	kobj_ns_drop(KOBJ_NS_TYPE_NET, to_ns_common(target->net));
@@ -1055,7 +1060,8 @@ static void srp_remove_target(struct 
srp_target_port *target)
 		srp_free_ch_ib(target, ch);
 	}
 	cancel_work_sync(&target->tl_err_work);
-	srp_rport_put(target->rport);
+	srp_remove_host(target->scsi_host);
+	scsi_remove_host(target->scsi_host);
 	kfree(target->ch);
 	target->ch = NULL;