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

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Message-Id: <20190412141327.2122-1-colin.king@canonical.com>
Date:   Fri, 12 Apr 2019 15:13:27 +0100
From:   Colin King <colin.king@...onical.com>
To:     Ariel Elior <aelior@...vell.com>, GR-everest-linux-l2@...vell.com,
        "David S . Miller" <davem@...emloft.net>, netdev@...r.kernel.org
Cc:     kernel-janitors@...r.kernel.org
Subject: [PATCH] qede: fix write to free'd pointer error and double free of ptp

From: Colin Ian King <colin.king@...onical.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.king@...onical.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