linux-kernel - [PATCH 3.12 067/155] target: Fix virtual LUN=0 target_configure

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Message-Id: <0848ace7f5f2cad22129293e64460eb8279564b6.1428411004.git.jslaby@suse.cz>
Date:	Tue,  7 Apr 2015 14:50:36 +0200
From:	Jiri Slaby <jslaby@...e.cz>
To:	stable@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org,
	Nicholas Bellinger <nab@...ux-iscsi.org>,
	Claudio Fleiner <cmf@...erainc.com>,
	Christoph Hellwig <hch@....de>, Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH 3.12 067/155] target: Fix virtual LUN=0 target_configure_device failure OOPs

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

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

===============

commit 5f7da044f8bc1cfb21c962edf34bd5699a76e7ae upstream.

This patch fixes a NULL pointer dereference triggered by a late
target_configure_device() -> alloc_workqueue() failure that results
in target_free_device() being called with DF_CONFIGURED already set,
which subsequently OOPses in destroy_workqueue() code.

Currently this only happens at modprobe target_core_mod time when
core_dev_setup_virtual_lun0() -> target_configure_device() fails,
and the explicit target_free_device() gets called.

To address this bug originally introduced by commit 0fd97ccf45, go
ahead and move DF_CONFIGURED to end of target_configure_device()
code to handle this special failure case.

Reported-by: Claudio Fleiner <cmf@...erainc.com>
Cc: Claudio Fleiner <cmf@...erainc.com>
Cc: Christoph Hellwig <hch@....de>
Signed-off-by: Nicholas Bellinger <nab@...ux-iscsi.org>
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
---
 drivers/target/target_core_device.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
index c67a56e7ee1c..4711e437479e 100644
--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -1492,8 +1492,6 @@ int target_configure_device(struct se_device *dev)
 	ret = dev->transport->configure_device(dev);
 	if (ret)
 		goto out;
-	dev->dev_flags |= DF_CONFIGURED;
-
 	/*
 	 * XXX: there is not much point to have two different values here..
 	 */
@@ -1555,6 +1553,8 @@ int target_configure_device(struct se_device *dev)
 	list_add_tail(&dev->g_dev_node, &g_device_list);
 	mutex_unlock(&g_device_mutex);
 
+	dev->dev_flags |= DF_CONFIGURED;
+
 	return 0;
 
 out_free_alua:
-- 
2.3.4

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