| Message ID | 20191015182549.GA13772@embeddedor (mailing list archive) |
|---|---|
| State | Superseded, archived |
| Headers | show |
| Series | platform/x86: huawei-wmi: Fix misuse of strcmp() function | expand |
Hi Gustavo, On Tue, 2019-10-15 at 13:25 -0500, Gustavo A. R. Silva wrote: > Comparing the result of strcmp directly with 1 may cause it to be > misinterpreted. Note that strcmp may return an integer besides -1, > 0, or 1. > > Fix this by returning -ENODEV only when strcmp() returns a value > other than 0. > > Addresses-Coverity-ID: 1487035 ("Misuse of memcmp-style function") > Fixes: b7527d0f4502 ("platform/x86: huawei-wmi: Add battery charging > thresholds") > Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> > --- > drivers/platform/x86/huawei-wmi.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/platform/x86/huawei-wmi.c > b/drivers/platform/x86/huawei-wmi.c > index 6720f78c60c2..b43f76acbfea 100644 > --- a/drivers/platform/x86/huawei-wmi.c > +++ b/drivers/platform/x86/huawei-wmi.c > @@ -470,7 +470,7 @@ static DEVICE_ATTR_RW(charge_control_thresholds); > static int huawei_wmi_battery_add(struct power_supply *battery) > { > /* Huawei laptops come with one battery only */ > - if (strcmp(battery->desc->name, "BAT") != 1) Note we don't have a battery number in BATx, strcmp would return 1 if battery->desc->name is "BAT0" or any one digit. This is a desired behavior where some Huawei laptops identify the first battery as "BAT1" and this would match if name is greater than "BAT" by one digit. Maybe strcmp(battery->desc->name, "BAT") < 0 is a better way to go. > + if (strcmp(battery->desc->name, "BAT")) > return -ENODEV; Now this would always return ENODEV. Thank you, Ayman > > device_create_file(&battery->dev, > &dev_attr_charge_control_start_threshold);
Hi Ayman, On 10/15/19 14:08, ayman.bagabas@gmail.com wrote: >> /* Huawei laptops come with one battery only */ >> - if (strcmp(battery->desc->name, "BAT") != 1) > > Note we don't have a battery number in BATx, strcmp would return 1 if > battery->desc->name is "BAT0" or any one digit. This is a desired > behavior where some Huawei laptops identify the first battery as "BAT1" > and this would match if name is greater than "BAT" by one digit. > Great to know this is not a bug. I don't think there is any other instance in the whole codebase like this one: strcmp(...) != 1 So, that's an odd thing to see... Maybe you can consider adding the whole description above as a code comment? :) > Maybe strcmp(battery->desc->name, "BAT") < 0 is a better way to go. > Yeah; this is bit more specific. Thanks! -- Gustavo
diff --git a/drivers/platform/x86/huawei-wmi.c b/drivers/platform/x86/huawei-wmi.c index 6720f78c60c2..b43f76acbfea 100644 --- a/drivers/platform/x86/huawei-wmi.c +++ b/drivers/platform/x86/huawei-wmi.c @@ -470,7 +470,7 @@ static DEVICE_ATTR_RW(charge_control_thresholds); static int huawei_wmi_battery_add(struct power_supply *battery) { /* Huawei laptops come with one battery only */ - if (strcmp(battery->desc->name, "BAT") != 1) + if (strcmp(battery->desc->name, "BAT")) return -ENODEV; device_create_file(&battery->dev, &dev_attr_charge_control_start_threshold);
Comparing the result of strcmp directly with 1 may cause it to be misinterpreted. Note that strcmp may return an integer besides -1, 0, or 1. Fix this by returning -ENODEV only when strcmp() returns a value other than 0. Addresses-Coverity-ID: 1487035 ("Misuse of memcmp-style function") Fixes: b7527d0f4502 ("platform/x86: huawei-wmi: Add battery charging thresholds") Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> --- drivers/platform/x86/huawei-wmi.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)