Patch "target: Don't BUG_ON during NodeACL dynamic -> explicit conversion" has been added to the 4.9-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    target: Don't BUG_ON during NodeACL dynamic -> explicit conversion

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     target-don-t-bug_on-during-nodeacl-dynamic-explicit-conversion.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 391e2a6de9781e4906dd7e0b1cc097050bf43e11 Mon Sep 17 00:00:00 2001
From: Nicholas Bellinger <nab@linux-iscsi.org>
Date: Sun, 23 Oct 2016 14:28:15 -0700
Subject: target: Don't BUG_ON during NodeACL dynamic -> explicit conversion

From: Nicholas Bellinger <nab@linux-iscsi.org>

commit 391e2a6de9781e4906dd7e0b1cc097050bf43e11 upstream.

After the v4.2+ RCU conversion to se_node_acl->lun_entry_hlist,
a BUG_ON() was added in core_enable_device_list_for_node() to
detect when the located orig->se_lun_acl contains an existing
se_lun_acl pointer reference.

However, this scenario can happen when a dynamically generated
NodeACL is being converted to an explicit NodeACL, when the
explicit NodeACL contains a different LUN mapping than the
default provided by the WWN endpoint.

So instead of triggering BUG_ON(), go ahead and fail instead
following the original pre RCU conversion logic.

Reported-by: Benjamin ESTRABAUD <ben.estrabaud@mpstor.com>
Cc: Benjamin ESTRABAUD <ben.estrabaud@mpstor.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/target/target_core_device.c |   10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -351,7 +351,15 @@ int core_enable_device_list_for_node(
 			kfree(new);
 			return -EINVAL;
 		}
-		BUG_ON(orig->se_lun_acl != NULL);
+		if (orig->se_lun_acl != NULL) {
+			pr_warn_ratelimited("Detected existing explicit"
+				" se_lun_acl->se_lun_group reference for %s"
+				" mapped_lun: %llu, failing\n",
+				 nacl->initiatorname, mapped_lun);
+			mutex_unlock(&nacl->lun_entry_mutex);
+			kfree(new);
+			return -EINVAL;
+		}
 
 		rcu_assign_pointer(new->se_lun, lun);
 		rcu_assign_pointer(new->se_lun_acl, lun_acl);


Patches currently in stable-queue which might be from nab@linux-iscsi.org are

queue-4.9/target-fix-compare_and_write-ref-leak-for-non-good-status.patch
queue-4.9/target-fix-multi-session-dynamic-se_node_acl-double-free-oops.patch
queue-4.9/target-use-correct-scsi-status-during-extended_copy-exception.patch
queue-4.9/ibmvscsis-add-sgl-limit.patch
queue-4.9/target-don-t-bug_on-during-nodeacl-dynamic-explicit-conversion.patch
queue-4.9/target-fix-early-transport_generic_handle_tmr-abort-scenario.patch