[PATCH] qede: fix write to free'd pointer error and double free of ptp

[Colin King]

From: Colin Ian King <colin.k...@canonical.com>

The err2 error return path calls qede_ptp_disable that cleans up
on an error and frees ptp. After this, the free'd ptp is dereferenced
when ptp->clock is set to NULL and the code falls-through to error
path err1 that frees ptp again.

Fix this by calling qede_ptp_disable and exiting via an error
return path that does not set ptp->clock or kfree ptp.

Addresses-Coverity: ("Write to pointer after free")
Fixes: 035744975aec ("qede: Add support for PTP resource locking.")

Signed-off-by: Colin Ian King <colin.k...@canonical.com>
---
 drivers/net/ethernet/qlogic/qede/qede_ptp.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/qlogic/qede/qede_ptp.c 
b/drivers/net/ethernet/qlogic/qede/qede_ptp.c
index 5f3f42a25361..7923dbd3b810 100644
--- a/drivers/net/ethernet/qlogic/qede/qede_ptp.c
+++ b/drivers/net/ethernet/qlogic/qede/qede_ptp.c
@@ -490,18 +490,17 @@ int qede_ptp_enable(struct qede_dev *edev, bool init_tc)
 
        ptp->clock = ptp_clock_register(&ptp->clock_info, &edev->pdev->dev);
        if (IS_ERR(ptp->clock)) {
-               rc = -EINVAL;
                DP_ERR(edev, "PTP clock registration failed\n");
-               goto err2;
+               qede_ptp_disable(edev);
+               rc = -EINVAL;
+               goto err2;
        }
 
        return 0;
 
-err2:
-       qede_ptp_disable(edev);
-       ptp->clock = NULL;
 err1:
        kfree(ptp);
+err2:
        edev->ptp = NULL;
 
        return rc;
-- 
2.20.1