linux-kernel - [PATCH] spi: bcm-qspi: return error if neither hif

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Message-Id: <20230629134306.95823-1-jonas.gorski@gmail.com>
Date:   Thu, 29 Jun 2023 15:43:05 +0200
From:   Jonas Gorski <jonas.gorski@...il.com>
To:     Kamal Dasu <kdasu.kdev@...il.com>,
        Broadcom internal kernel review list 
        <bcm-kernel-feedback-list@...adcom.com>,
        Mark Brown <broonie@...nel.org>
Cc:     linux-spi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] spi: bcm-qspi: return error if neither hif_mspi nor mspi is available

If neither a "hif_mspi" nor "mspi" resource is present, the driver will
just early exit in probe but still return success. Apart from not doing
anything meaningful, this would then also lead to a null pointer access
on removal, as platform_get_drvdata() would return NULL, which it would
then try to dereferce when trying to unregister the spi master.

Fix this by unconditionally calling devm_ioremap_resource(), as it can
handle a NULL res and will then return a viable ERR_PTR() if we get one.

The "return 0;" was previously a "goto qspi_resource_err;" where then
ret was returned, but since ret was still initialized to 0 at this place
this was a valid conversion in 63c5395bb7a9 ("spi: bcm-qspi: Fix
use-after-free on unbind"). The issue was not introduced by this commit,
only made more obvious.

Fixes: fa236a7ef240 ("spi: bcm-qspi: Add Broadcom MSPI driver")
Signed-off-by: Jonas Gorski <jonas.gorski@...il.com>
---
Found by looking a the driver while comparing it to its bindings.

Only build tested, not runtested.

 drivers/spi/spi-bcm-qspi.c | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/drivers/spi/spi-bcm-qspi.c b/drivers/spi/spi-bcm-qspi.c
index 6b46a3b67c41..d91dfbe47aa5 100644
--- a/drivers/spi/spi-bcm-qspi.c
+++ b/drivers/spi/spi-bcm-qspi.c
@@ -1543,13 +1543,9 @@ int bcm_qspi_probe(struct platform_device *pdev,
 		res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
 						   "mspi");

-	if (res) {
-		qspi->base[MSPI]  = devm_ioremap_resource(dev, res);
-		if (IS_ERR(qspi->base[MSPI]))
-			return PTR_ERR(qspi->base[MSPI]);
-	} else {
-		return 0;
-	}
+	qspi->base[MSPI]  = devm_ioremap_resource(dev, res);
+	if (IS_ERR(qspi->base[MSPI]))
+		return PTR_ERR(qspi->base[MSPI]);

 	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "bspi");
 	if (res) {
-- 
2.34.1