From:   Erik Stromdahl <erik.stromdahl@gmail.com>
To:     kvalo@qca.qualcomm.com, linux-wireless@vger.kernel.org,
        ath10k@lists.infradead.org
Cc:     Erik Stromdahl <erik.stromdahl@gmail.com>
Subject: [PATCH 6/6] ath10k: sdio: replace skb_trim with explicit set of skb->len
Date:   Tue,  9 Apr 2019 21:08:51 +0200
Message-Id: <20190409190851.4557-7-erik.stromdahl@gmail.com>
In-Reply-To: <20190409190851.4557-1-erik.stromdahl@gmail.com>
References: <20190409190851.4557-1-erik.stromdahl@gmail.com>
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Sender: linux-wireless-owner@vger.kernel.org
Precedence: bulk

This patch fixes a bug with padding of the skb data buffer.
Since skb_trim can only be used to reduce the skb len, it is useless when
we pad (increase the length of) the skb. Instead we must set skb->len
directly.

Signed-off-by: Erik Stromdahl <erik.stromdahl@gmail.com>
---
 drivers/net/wireless/ath/ath10k/sdio.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/ath/ath10k/sdio.c b/drivers/net/wireless/ath/ath10k/sdio.c
index 3eb241cb8a25..989e3f563f3d 100644
--- a/drivers/net/wireless/ath/ath10k/sdio.c
+++ b/drivers/net/wireless/ath/ath10k/sdio.c
@@ -1496,7 +1496,12 @@ static int ath10k_sdio_hif_tx_sg(struct ath10k *ar, u8 pipe_id,
 		skb = items[i].transfer_context;
 		padded_len = ath10k_sdio_calc_txrx_padded_len(ar_sdio,
 							      skb->len);
-		skb_trim(skb, padded_len);
+		/* FIXME: unsure if just extending the skb len is the right
+		 * thing to do since we might read outside the skb->data
+		 * buffer. But we really don't want to realloc the skb just to
+		 * pad the length.
+		 */
+		skb->len = padded_len;
 
 		/* Write TX data to the end of the mbox address space */
 		address = ar_sdio->mbox_addr[eid] + ar_sdio->mbox_size[eid] -
-- 
2.19.1