[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 <redacted>
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

On Sun, Dec 2, 2018 at 3:07 AM Nicholas Mc Guire [off-list ref] wrote:

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.

I think your assumption is correct.  Do you want to send a new and
better version?  :)

On Wed, Dec 05, 2018 at 02:42:55PM -0600, Li Yang wrote:

On Sun, Dec 2, 2018 at 3:07 AM Nicholas Mc Guire [off-list ref] wrote:

quoted

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.

I think your assumption is correct.  Do you want to send a new and
better version?  :)

The issue was actually more general that I did not find a reliable
method to assure that some object is *always* RO. Even for device
tree data it was not clear to me if there could be systems where
it is not RO.
Anyway - will send the version using devm_kstrdup_const() then.

thx!
hofrat

quoted

Signed-off-by: Nicholas Mc Guire <redacted>
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