linux-kernel - [RFC PATCH] soc: fsl: guts: handle devm

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Date:   Sun,  2 Dec 2018 10:00:58 +0100
From:   Nicholas Mc Guire <hofrat@...dl.org>
To:     Li Yang <leoyang.li@....com>
Cc:     linuxppc-dev@...ts.ozlabs.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Nicholas Mc Guire <hofrat@...dl.org>
Subject: [RFC PATCH] soc: fsl: guts: handle devm_kstrdup() failure

devm_kstrdup() may return NULL if internal allocation failed.
soc_dev_attr.machine  should be checked (although its only use
in pr_info() would be safe even with a NULL). Therefor
in the unlikely case of allocation failure, fsl_guts_probe() returns
-ENOMEM as this allocating failing is an indication of something
more serious going wrong at system level.

As  machine  is from the device tree which I assume to be RO - if
that assumption is always correct - a better alternative would be
to use devm_kstrdup_const() here. That would then simply copy the
reference to the RO data and not perform any allocation at all.

Signed-off-by: Nicholas Mc Guire <hofrat@...dl.org>
Fixes: a6fc3b698130 ("soc: fsl: add GUTS driver for QorIQ platforms")
---

Problem located by experimental coccinelle script

Patch was compile tested with: multi_v7_defconfig (implies FSL_GUTS=y)

Patch is against 4.20-rc4 (localversion-next is next-20181130)

 drivers/soc/fsl/guts.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/soc/fsl/guts.c b/drivers/soc/fsl/guts.c
index 302e0c8..a0c751b 100644
--- a/drivers/soc/fsl/guts.c
+++ b/drivers/soc/fsl/guts.c
@@ -156,8 +156,11 @@ static int fsl_guts_probe(struct platform_device *pdev)
 	if (of_property_read_string(root, "model", &machine))
 		of_property_read_string_index(root, "compatible", 0, &machine);
 	of_node_put(root);
-	if (machine)
+	if (machine) {
 		soc_dev_attr.machine = devm_kstrdup(dev, machine, GFP_KERNEL);
+		if (!soc_dev_attr.machine)
+			return -ENOMEM;
+	}
 
 	svr = fsl_guts_get_svr();
 	soc_die = fsl_soc_die_match(svr, fsl_soc_die);
-- 
2.1.4