target: Fix alua_access_state attribute OOPs for un-configured devices

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@tiger-computing.co.uk>
Reported-by: Philip Gaw <pgaw@darktech.org.uk>
Cc: Chris Boot <crb@tiger-computing.co.uk>
Cc: Philip Gaw <pgaw@darktech.org.uk>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/target/target_core_configfs.c b/drivers/target/target_core_configfs.c
index 4a8bd36..8cda408 100644 (file)
--- a/drivers/target/target_core_configfs.c
+++ b/drivers/target/target_core_configfs.c
@@ -2034,6 +2034,11 @@ static ssize_t target_core_alua_tg_pt_gp_store_attr_alua_access_state(
                        " 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 = strict_strtoul(page, 0, &tmp);
        if (ret < 0) {