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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, Aashay Shringarpure <aashay@google.com>,
        Yi Chou <yich@google.com>,
        Shervin Oloumi <enlightened@google.com>,
        Grant Grundler <grundler@chromium.org>,
        "David S. Miller" <davem@davemloft.net>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.15 123/132] net: atlantic: fix "frag[0] not initialized"
Date:   Mon, 23 May 2022 19:05:32 +0200
Message-Id: <20220523165844.013420895@linuxfoundation.org>
In-Reply-To: <20220523165823.492309987@linuxfoundation.org>
References: <20220523165823.492309987@linuxfoundation.org>
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From: Grant Grundler <grundler@chromium.org>

[ Upstream commit 62e0ae0f4020250f961cf8d0103a4621be74e077 ]

In aq_ring_rx_clean(), if buff->is_eop is not set AND
buff->len < AQ_CFG_RX_HDR_SIZE, then hdr_len remains equal to
buff->len and skb_add_rx_frag(xxx, *0*, ...) is not called.

The loop following this code starts calling skb_add_rx_frag() starting
with i=1 and thus frag[0] is never initialized. Since i is initialized
to zero at the top of the primary loop, we can just reference and
post-increment i instead of hardcoding the 0 when calling
skb_add_rx_frag() the first time.

Reported-by: Aashay Shringarpure <aashay@google.com>
Reported-by: Yi Chou <yich@google.com>
Reported-by: Shervin Oloumi <enlightened@google.com>
Signed-off-by: Grant Grundler <grundler@chromium.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/ethernet/aquantia/atlantic/aq_ring.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/aquantia/atlantic/aq_ring.c b/drivers/net/ethernet/aquantia/atlantic/aq_ring.c
index 72f8751784c3..7cf5a48e9a7d 100644
--- a/drivers/net/ethernet/aquantia/atlantic/aq_ring.c
+++ b/drivers/net/ethernet/aquantia/atlantic/aq_ring.c
@@ -445,7 +445,7 @@ int aq_ring_rx_clean(struct aq_ring_s *self,
 		       ALIGN(hdr_len, sizeof(long)));
 
 		if (buff->len - hdr_len > 0) {
-			skb_add_rx_frag(skb, 0, buff->rxdata.page,
+			skb_add_rx_frag(skb, i++, buff->rxdata.page,
 					buff->rxdata.pg_off + hdr_len,
 					buff->len - hdr_len,
 					AQ_CFG_RX_FRAME_MAX);
@@ -454,7 +454,6 @@ int aq_ring_rx_clean(struct aq_ring_s *self,
 
 		if (!buff->is_eop) {
 			buff_ = buff;
-			i = 1U;
 			do {
 				next_ = buff_->next;
 				buff_ = &self->buff_ring[next_];
-- 
2.35.1