linux-kernel - [PATCH 5.10 077/105] spi: bcm2835: bcm2835_spi_handle_err(): fix NULL pointer deref for non DMA transfers

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Message-Id: <20220727161015.162983431@linuxfoundation.org>
Date:   Wed, 27 Jul 2022 18:11:03 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Lukas Wunner <lukas@...ner.de>,
        Marc Kleine-Budde <mkl@...gutronix.de>,
        Mark Brown <broonie@...nel.org>
Subject: [PATCH 5.10 077/105] spi: bcm2835: bcm2835_spi_handle_err(): fix NULL pointer deref for non DMA transfers

From: Marc Kleine-Budde <mkl@...gutronix.de>

commit 4ceaa684459d414992acbefb4e4c31f2dfc50641 upstream.

In case a IRQ based transfer times out the bcm2835_spi_handle_err()
function is called. Since commit 1513ceee70f2 ("spi: bcm2835: Drop
dma_pending flag") the TX and RX DMA transfers are unconditionally
canceled, leading to NULL pointer derefs if ctlr->dma_tx or
ctlr->dma_rx are not set.

Fix the NULL pointer deref by checking that ctlr->dma_tx and
ctlr->dma_rx are valid pointers before accessing them.

Fixes: 1513ceee70f2 ("spi: bcm2835: Drop dma_pending flag")
Cc: Lukas Wunner <lukas@...ner.de>
Signed-off-by: Marc Kleine-Budde <mkl@...gutronix.de>
Link: https://lore.kernel.org/r/20220719072234.2782764-1-mkl@pengutronix.de
Signed-off-by: Mark Brown <broonie@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/spi/spi-bcm2835.c |   12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

--- a/drivers/spi/spi-bcm2835.c
+++ b/drivers/spi/spi-bcm2835.c
@@ -1174,10 +1174,14 @@ static void bcm2835_spi_handle_err(struc
 	struct bcm2835_spi *bs = spi_controller_get_devdata(ctlr);
 
 	/* if an error occurred and we have an active dma, then terminate */
-	dmaengine_terminate_sync(ctlr->dma_tx);
-	bs->tx_dma_active = false;
-	dmaengine_terminate_sync(ctlr->dma_rx);
-	bs->rx_dma_active = false;
+	if (ctlr->dma_tx) {
+		dmaengine_terminate_sync(ctlr->dma_tx);
+		bs->tx_dma_active = false;
+	}
+	if (ctlr->dma_rx) {
+		dmaengine_terminate_sync(ctlr->dma_rx);
+		bs->rx_dma_active = false;
+	}
 	bcm2835_spi_undo_prologue(bs);
 
 	/* and reset */