iavf: fix potential deadlock on allocation failure

In iavf_adminq_task(), if kzalloc() fails to allocate the event.msg_buf,
the function will exit without releasing the adapter->crit_lock.

This is unlikely, but if it happens, the next access to that mutex will
deadlock.

Fix this by moving the unlock to the end of the function, and adding a new
label to allow jumping to the unlock portion of the function exit flow.

Fixes: fc2e6b3b132a ("iavf: Rework mutexes for better synchronisation")
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Rafal Romanowski <rafal.romanowski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

diff --git a/drivers/net/ethernet/intel/iavf/iavf_main.c b/drivers/net/ethernet/intel/iavf/iavf_main.c
index 3a88d413ddee3639e0ed61515da647c1d1363f53..939c8126eb437a3a07d8bd474d1de896eb928854 100644 (file)
--- a/drivers/net/ethernet/intel/iavf/iavf_main.c
+++ b/drivers/net/ethernet/intel/iavf/iavf_main.c
@@ -3264,7 +3264,7 @@ static void iavf_adminq_task(struct work_struct *work)
        event.buf_len = IAVF_MAX_AQ_BUF_SIZE;
        event.msg_buf = kzalloc(event.buf_len, GFP_KERNEL);
        if (!event.msg_buf)
-               goto out;
+               goto unlock;
 
        do {
                ret = iavf_clean_arq_element(hw, &event, &pending);
@@ -3279,7 +3279,6 @@ static void iavf_adminq_task(struct work_struct *work)
                if (pending != 0)
                        memset(event.msg_buf, 0, IAVF_MAX_AQ_BUF_SIZE);
        } while (pending);
-       mutex_unlock(&adapter->crit_lock);
 
        if (iavf_is_reset_in_progress(adapter))
                goto freedom;
@@ -3323,6 +3322,8 @@ static void iavf_adminq_task(struct work_struct *work)
 
 freedom:
        kfree(event.msg_buf);
+unlock:
+       mutex_unlock(&adapter->crit_lock);
 out:
        /* re-enable Admin queue interrupt cause */
        iavf_misc_irq_enable(adapter);