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From:   Vaishnav Achath <vaishnav.a@ti.com>
To:     <broonie@kernel.org>, <linux-kernel@vger.kernel.org>,
        <linux-spi@vger.kernel.org>
CC:     <vaishnav.a@ti.com>, <p.yadav@ti.com>, <vigneshr@ti.com>
Subject: [PATCH -next] spi: cadence-quadspi: Remove spi_master_put() in probe failure path
Date:   Wed, 1 Jun 2022 12:46:11 +0530
Message-ID: <20220601071611.11853-1-vaishnav.a@ti.com>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

Currently the spi_master is allocated by devm_spi_alloc_master()
and devres core manages the deallocation, but in probe failure
path spi_master_put() is being handled manually which causes
"refcount underflow use-after-free" warning when probe failure happens
after allocating spi_master.

Trimmed backtrace during failure:

refcount_t: underflow; use-after-free.
pc : refcount_warn_saturate+0xf4/0x144
Call trace:
refcount_warn_saturate
kobject_put
put_device
devm_spi_release_controller
devres_release_all

This commit makes relevant changes to remove spi_master_put() from probe
failure path.

Fixes: 606e5d408184 ("spi: cadence-quadspi: Handle spi_unregister_master() in remove()")

Signed-off-by: Vaishnav Achath <vaishnav.a@ti.com>
---
 drivers/spi/spi-cadence-quadspi.c | 19 +++++++------------
 1 file changed, 7 insertions(+), 12 deletions(-)

diff --git a/drivers/spi/spi-cadence-quadspi.c b/drivers/spi/spi-cadence-quadspi.c
index 2b9fc8449a62..72b1a5a2298c 100644
--- a/drivers/spi/spi-cadence-quadspi.c
+++ b/drivers/spi/spi-cadence-quadspi.c
@@ -1578,8 +1578,7 @@ static int cqspi_probe(struct platform_device *pdev)
 	ret = cqspi_of_get_pdata(cqspi);
 	if (ret) {
 		dev_err(dev, "Cannot get mandatory OF data.\n");
-		ret = -ENODEV;
-		goto probe_master_put;
+		return -ENODEV;
 	}
 
 	/* Obtain QSPI clock. */
@@ -1587,7 +1586,7 @@ static int cqspi_probe(struct platform_device *pdev)
 	if (IS_ERR(cqspi->clk)) {
 		dev_err(dev, "Cannot claim QSPI clock.\n");
 		ret = PTR_ERR(cqspi->clk);
-		goto probe_master_put;
+		return ret;
 	}
 
 	/* Obtain and remap controller address. */
@@ -1596,7 +1595,7 @@ static int cqspi_probe(struct platform_device *pdev)
 	if (IS_ERR(cqspi->iobase)) {
 		dev_err(dev, "Cannot remap controller address.\n");
 		ret = PTR_ERR(cqspi->iobase);
-		goto probe_master_put;
+		return ret;
 	}
 
 	/* Obtain and remap AHB address. */
@@ -1605,7 +1604,7 @@ static int cqspi_probe(struct platform_device *pdev)
 	if (IS_ERR(cqspi->ahb_base)) {
 		dev_err(dev, "Cannot remap AHB address.\n");
 		ret = PTR_ERR(cqspi->ahb_base);
-		goto probe_master_put;
+		return ret;
 	}
 	cqspi->mmap_phys_base = (dma_addr_t)res_ahb->start;
 	cqspi->ahb_size = resource_size(res_ahb);
@@ -1614,15 +1613,13 @@ static int cqspi_probe(struct platform_device *pdev)
 
 	/* Obtain IRQ line. */
 	irq = platform_get_irq(pdev, 0);
-	if (irq < 0) {
-		ret = -ENXIO;
-		goto probe_master_put;
-	}
+	if (irq < 0)
+		return -ENXIO;
 
 	pm_runtime_enable(dev);
 	ret = pm_runtime_resume_and_get(dev);
 	if (ret < 0)
-		goto probe_master_put;
+		return ret;
 
 	ret = clk_prepare_enable(cqspi->clk);
 	if (ret) {
@@ -1716,8 +1713,6 @@ static int cqspi_probe(struct platform_device *pdev)
 probe_clk_failed:
 	pm_runtime_put_sync(dev);
 	pm_runtime_disable(dev);
-probe_master_put:
-	spi_master_put(master);
 	return ret;
 }
 
-- 
2.17.1