netdev - [PATCH net] qede: avoid uninitialized entries in coal

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Date:   Fri, 24 Feb 2023 01:41:45 +0100
From:   Michal Schmidt <mschmidt@...hat.com>
To:     netdev@...r.kernel.org
Cc:     Manish Chopra <manishc@...vell.com>,
        Ariel Elior <aelior@...vell.com>,
        Alok Prasad <palok@...vell.com>
Subject: [PATCH net] qede: avoid uninitialized entries in coal_entry array

Even after commit 908d4bb7c54c ("qede: fix interrupt coalescing
configuration"), some entries of the coal_entry array may theoretically
be used uninitialized:

 1. qede_alloc_fp_array() allocates QEDE_MAX_RSS_CNT entries for
    coal_entry. The initial allocation uses kcalloc, so everything is
    initialized.
 2. The user sets a small number of queues (ethtool -L).
    coal_entry is reallocated for the actual small number of queues.
 3. The user sets a bigger number of queues.
    coal_entry is reallocated bigger. The added entries are not
    necessarily initialized.

In practice, the reallocations will actually keep using the originally
allocated region of memory, but we should not rely on it.

The reallocation is unnecessary. coal_entry can always have
QEDE_MAX_RSS_CNT entries.

Fixes: 908d4bb7c54c ("qede: fix interrupt coalescing configuration")
Signed-off-by: Michal Schmidt <mschmidt@...hat.com>
---
 drivers/net/ethernet/qlogic/qede/qede_main.c | 21 +++++++-------------
 1 file changed, 7 insertions(+), 14 deletions(-)

diff --git a/drivers/net/ethernet/qlogic/qede/qede_main.c b/drivers/net/ethernet/qlogic/qede/qede_main.c
index 4a3c3b5fb4a1..261f982ca40d 100644
--- a/drivers/net/ethernet/qlogic/qede/qede_main.c
+++ b/drivers/net/ethernet/qlogic/qede/qede_main.c
@@ -963,7 +963,6 @@ static int qede_alloc_fp_array(struct qede_dev *edev)
 {
 	u8 fp_combined, fp_rx = edev->fp_num_rx;
 	struct qede_fastpath *fp;
-	void *mem;
 	int i;
 
 	edev->fp_array = kcalloc(QEDE_QUEUE_CNT(edev),
@@ -974,20 +973,14 @@ static int qede_alloc_fp_array(struct qede_dev *edev)
 	}
 
 	if (!edev->coal_entry) {
-		mem = kcalloc(QEDE_MAX_RSS_CNT(edev),
-			      sizeof(*edev->coal_entry), GFP_KERNEL);
-	} else {
-		mem = krealloc(edev->coal_entry,
-			       QEDE_QUEUE_CNT(edev) * sizeof(*edev->coal_entry),
-			       GFP_KERNEL);
-	}
-
-	if (!mem) {
-		DP_ERR(edev, "coalesce entry allocation failed\n");
-		kfree(edev->coal_entry);
-		goto err;
+		edev->coal_entry = kcalloc(QEDE_MAX_RSS_CNT(edev),
+					   sizeof(*edev->coal_entry),
+					   GFP_KERNEL);
+		if (!edev->coal_entry) {
+			DP_ERR(edev, "coalesce entry allocation failed\n");
+			goto err;
+		}
 	}
-	edev->coal_entry = mem;
 
 	fp_combined = QEDE_QUEUE_CNT(edev) - fp_rx - edev->fp_num_tx;
 
-- 
2.39.1