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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Haiyue Wang <haiyue.wang@intel.com>,
        Catherine Sullivan <csully@google.com>,
        "David S. Miller" <davem@davemloft.net>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.13 093/300] gve: fix the wrong AdminQ buffer overflow check
Date:   Mon, 13 Sep 2021 15:12:34 +0200
Message-Id: <20210913131112.525394716@linuxfoundation.org>
In-Reply-To: <20210913131109.253835823@linuxfoundation.org>
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From: Haiyue Wang <haiyue.wang@intel.com>

[ Upstream commit 63a9192b8fa1ea55efeba1f18fad52bb24d9bf12 ]

The 'tail' pointer is also free-running count, so it needs to be masked
as 'adminq_prod_cnt' does, to become an index value of AdminQ buffer.

Fixes: 5cdad90de62c ("gve: Batch AQ commands for creating and destroying queues.")
Signed-off-by: Haiyue Wang <haiyue.wang@intel.com>
Reviewed-by: Catherine Sullivan <csully@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/ethernet/google/gve/gve_adminq.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/google/gve/gve_adminq.c b/drivers/net/ethernet/google/gve/gve_adminq.c
index 53864f200599..b175f2b2f5bc 100644
--- a/drivers/net/ethernet/google/gve/gve_adminq.c
+++ b/drivers/net/ethernet/google/gve/gve_adminq.c
@@ -233,7 +233,8 @@ static int gve_adminq_issue_cmd(struct gve_priv *priv,
 	tail = ioread32be(&priv->reg_bar0->adminq_event_counter);
 
 	// Check if next command will overflow the buffer.
-	if (((priv->adminq_prod_cnt + 1) & priv->adminq_mask) == tail) {
+	if (((priv->adminq_prod_cnt + 1) & priv->adminq_mask) ==
+	    (tail & priv->adminq_mask)) {
 		int err;
 
 		// Flush existing commands to make room.
@@ -243,7 +244,8 @@ static int gve_adminq_issue_cmd(struct gve_priv *priv,
 
 		// Retry.
 		tail = ioread32be(&priv->reg_bar0->adminq_event_counter);
-		if (((priv->adminq_prod_cnt + 1) & priv->adminq_mask) == tail) {
+		if (((priv->adminq_prod_cnt + 1) & priv->adminq_mask) ==
+		    (tail & priv->adminq_mask)) {
 			// This should never happen. We just flushed the
 			// command queue so there should be enough space.
 			return -ENOMEM;
-- 
2.30.2