3.16.62-rc1 review patch. If anyone has any objections, please let me know.
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From: "H. Nikolaus Schaller" hns@goldelico.com
commit 932d47448c3caa0fa99e84d7f5bc302aa286efd8 upstream.
We did have sporadic problems in the pinctrl framework during boot where a pin group name unexpectedly became NULL leading to a NULL dereference in strcmp.
Detailled analysis of the failing cases did reveal that there were two devm allocated objects close to each other. The second one was the affected group_desc in pinmux and the first one was the psy_desc->properties buffer of the gab driver.
Review of the gab code showed that the address calculation for one memcpy() is wrong. It does
properties + sizeof(type) * index
but C is defined to do the index multiplication already for pointer + integer additions. Hence the factor was applied twice and the memcpy() does write outside of the properties buffer. Sometimes it happened to be the pinctrl and triggered the strcmp(NULL).
Anyways, it is overkill to use a memcpy() here instead of a simple assignment, which is easier to read and has less risk for wrong address calculations. So we change code to a simple assignment.
If we initialize the index to the first free location, we can even remove the local variable 'properties'.
This bug seems to exist right from the beginning in 3.7-rc1 in
commit e60fea794e6e ("power: battery: Generic battery driver using IIO")
Signed-off-by: H. Nikolaus Schaller hns@goldelico.com Fixes: e60fea794e6e ("power: battery: Generic battery driver using IIO") Signed-off-by: Sebastian Reichel sebastian.reichel@collabora.co.uk [bwh: Backported to 3.16: - s/psy_desc/psy/g - Adjust filename] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- drivers/power/generic-adc-battery.c | 14 ++++---------- 1 file changed, 4 insertions(+), 10 deletions(-)
--- a/drivers/power/generic-adc-battery.c +++ b/drivers/power/generic-adc-battery.c @@ -241,10 +241,9 @@ static int gab_probe(struct platform_dev struct gab *adc_bat; struct power_supply *psy; struct gab_platform_data *pdata = pdev->dev.platform_data; - enum power_supply_property *properties; int ret = 0; int chan; - int index = 0; + int index = ARRAY_SIZE(gab_props);
adc_bat = devm_kzalloc(&pdev->dev, sizeof(*adc_bat), GFP_KERNEL); if (!adc_bat) { @@ -276,8 +275,6 @@ static int gab_probe(struct platform_dev }
memcpy(psy->properties, gab_props, sizeof(gab_props)); - properties = (enum power_supply_property *) - ((char *)psy->properties + sizeof(gab_props));
/* * getting channel from iio and copying the battery properties @@ -291,15 +288,12 @@ static int gab_probe(struct platform_dev adc_bat->channel[chan] = NULL; } else { /* copying properties for supported channels only */ - memcpy(properties + sizeof(*(psy->properties)) * index, - &gab_dyn_props[chan], - sizeof(gab_dyn_props[chan])); - index++; + psy->properties[index++] = gab_dyn_props[chan]; } }
/* none of the channels are supported so let's bail out */ - if (index == 0) { + if (index == ARRAY_SIZE(gab_props)) { ret = -ENODEV; goto second_mem_fail; } @@ -310,7 +304,7 @@ static int gab_probe(struct platform_dev * as come channels may be not be supported by the device.So * we need to take care of that. */ - psy->num_properties = ARRAY_SIZE(gab_props) + index; + psy->num_properties = index;
ret = power_supply_register(&pdev->dev, psy); if (ret)