Messages in this thread | | | Date | Thu, 27 Aug 2020 15:16:56 -0700 | From | Kees Cook <> | Subject | Re: [Cocci] [PATCH] usb: atm: don't use snprintf() for sysfs attrs |
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On Thu, Aug 27, 2020 at 03:11:57PM -0700, Joe Perches wrote: > On Thu, 2020-08-27 at 22:03 +0000, David Laight wrote: > > From: Joe Perches > > > Sent: 27 August 2020 21:30 > > ... > > > Perhaps what's necessary is to find any > > > appropriate .show function and change > > > any use of strcpy/sprintf within those > > > function to some other name. > > > > > > For instance: > > > > > > drivers/isdn/mISDN/core.c-static ssize_t name_show(struct device *dev, > > > drivers/isdn/mISDN/core.c- struct device_attribute *attr, char *buf) > > > drivers/isdn/mISDN/core.c-{ > > > drivers/isdn/mISDN/core.c: strcpy(buf, dev_name(dev)); > > > drivers/isdn/mISDN/core.c- return strlen(buf); > > > drivers/isdn/mISDN/core.c-} > > > drivers/isdn/mISDN/core.c-static DEVICE_ATTR_RO(name); > > > > That form ends up calculating the string length twice. > > Better would be: > > len = strlen(msg); > > memcpy(buf, msg, len); > > return len; > > or given clang's requirement for stpcpy > > return stpcpy(buf, dev_name(dev)) - buf; > > (I do not advocate for this ;)
Heh. And humans aren't allowed to use stpcpy() in the kernel. :)
-- Kees Cook
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