[PATCH 3.8 022/116] IB/srp: Fix a sporadic crash triggered by cable pulling

From: Kamal Mostafa
Date: Tue Jul 22 2014 - 18:26:37 EST


3.8.13.27 -stable review patch. If anyone has any objections, please let me know.

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

From: Bart Van Assche <bvanassche@xxxxxxx>

commit 024ca90151f5e4296d30f72c13ff9a075e23c9ec upstream.

Avoid that the loops that iterate over the request ring can encounter
a pointer to a SCSI command in req->scmnd that is no longer associated
with that request. If the function srp_unmap_data() is invoked twice
for a SCSI command that is not in flight then that would cause
ib_fmr_pool_unmap() to be invoked with an invalid pointer as argument,
resulting in a kernel oops.

Reported-by: Sagi Grimberg <sagig@xxxxxxxxxxxx>
Reference: http://thread.gmane.org/gmane.linux.drivers.rdma/19068/focus=19069
Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx>
Reviewed-by: Sagi Grimberg <sagig@xxxxxxxxxxxx>
Signed-off-by: Roland Dreier <roland@xxxxxxxxxxxxxxx>
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
---
drivers/infiniband/ulp/srp/ib_srp.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c
index e070166..5682e8e 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.c
+++ b/drivers/infiniband/ulp/srp/ib_srp.c
@@ -1410,6 +1410,12 @@ err_unmap:
err_iu:
srp_put_tx_iu(target, iu, SRP_IU_CMD);

+ /*
+ * Avoid that the loops that iterate over the request ring can
+ * encounter a dangling SCSI command pointer.
+ */
+ req->scmnd = NULL;
+
spin_lock_irqsave(&target->lock, flags);
list_add(&req->list, &target->free_reqs);

--
1.9.1

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