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

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

From: Bart Van Assche <bvanass...@acm.org>

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 <sa...@mellanox.com>
Reference: http://thread.gmane.org/gmane.linux.drivers.rdma/19068/focus=19069
Signed-off-by: Bart Van Assche <bvanass...@acm.org>
Reviewed-by: Sagi Grimberg <sa...@mellanox.com>
Signed-off-by: Roland Dreier <rol...@purestorage.com>
Signed-off-by: Kamal Mostafa <ka...@canonical.com>
---
 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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