[PATCH 4.9 25/60] target: Dont BUG_ON during NodeACL dynamic -> explicit conversion

From: Greg Kroah-Hartman
Date: Mon Feb 13 2017 - 08:20:57 EST

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


From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>

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@xxxxxxxxxx>
Cc: Benjamin ESTRABAUD <ben.estrabaud@xxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

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(
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);