[PATCH 3.14 72/78] target: Fix alua_access_state attribute OOPs for un-configured devices

[Greg Kroah-Hartman]

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

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

From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>

commit f1453773514bb8b0bba0716301e8c8f17f8d39c7 upstream.

This patch fixes a OOPs where an attempt to write to the per-device
alua_access_state configfs attribute at:

  /sys/kernel/config/target/core/$HBA/$DEV/alua/$TG_PT_GP/alua_access_state

results in an NULL pointer dereference when the backend device has not
yet been configured.

This patch adds an explicit check for DF_CONFIGURED, and fails with
-ENODEV to avoid this case.

Reported-by: Chris Boot <crb@xxxxxxxxxxxxxxxxxxxxx>
Reported-by: Philip Gaw <pgaw@xxxxxxxxxxxxxxx>
Cc: Chris Boot <crb@xxxxxxxxxxxxxxxxxxxxx>
Cc: Philip Gaw <pgaw@xxxxxxxxxxxxxxx>
Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/target/target_core_configfs.c |    5 +++++
 1 file changed, 5 insertions(+)

--- a/drivers/target/target_core_configfs.c
+++ b/drivers/target/target_core_configfs.c
@@ -2223,6 +2223,11 @@ static ssize_t target_core_alua_tg_pt_gp
 			" tg_pt_gp ID: %hu\n", tg_pt_gp->tg_pt_gp_valid_id);
 		return -EINVAL;
 	}
+	if (!(dev->dev_flags & DF_CONFIGURED)) {
+		pr_err("Unable to set alua_access_state while device is"
+		       " not configured\n");
+		return -ENODEV;
+	}
 
 	ret = kstrtoul(page, 0, &tmp);
 	if (ret < 0) {


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