Hi all, On 8/27/20 10:42 PM, Julia Lawall wrote: > > > On Thu, 27 Aug 2020, Joe Perches wrote: > >> On Thu, 2020-08-27 at 15:48 +0100, Alex Dewar wrote: >>> On Thu, Aug 27, 2020 at 03:41:06PM +0200, Rasmus Villemoes wrote: >>>> On 27/08/2020 15.18, Alex Dewar wrote: >>>>> On Thu, Aug 27, 2020 at 09:15:37AM +0200, Greg Kroah-Hartman wrote: >>>>>> On Thu, Aug 27, 2020 at 08:42:06AM +0200, Rasmus Villemoes wrote: >>>>>>> On 25/08/2020 00.23, Alex Dewar wrote: >>>>>>>> kernel/cpu.c: don't use snprintf() for sysfs attrs >>>>>>>> >>>>>>>> As per the documentation (Documentation/filesystems/sysfs.rst), >>>>>>>> snprintf() should not be used for formatting values returned by sysfs. Just FYI, I've send an addition to the device_attr_show.cocci script[1] to turn simple cases of snprintf (e.g. "%i") to sprintf. Looks like many developers would like it more than changing snprintf to scnprintf. As for me, I don't like the idea of automated altering of the original logic from bounded snprint to unbouded one with sprintf. [1] https://lkml.org/lkml/2020/8/13/786 Regarding current device_attr_show.cocci implementation, it detects the functions by declaration: ssize_t any_name(struct device *dev, struct device_attribute *attr, char *buf) and I limited the check to: "return snprintf" pattern because there are already too many warnings. Actually, it looks more correct to check for: ssize_t show(struct device *dev, struct device_attribute *attr, char *buf) { <... * snprintf@p(...); ...> } This pattern should also highlight the snprintf calls there we save returned value in a var, e.g.: ret += snprintf(...); ... ret += snprintf(...); ... ret += snprintf(...); return ret; > > Something like > > identifier f; > fresh identifier = "sysfs" ## f; > > may be useful. Let me know if further help is needed. Initially, I wrote the rule to search for DEVICE_ATTR(..., ..., func_name, ...) functions. However, it looks like matching function prototype is enough. At least, I failed to find false positives. I rejected the initial DEVICE_ATTR() searching because I thought that it's impossible to handle DEVICE_ATTR_RO()/DEVICE_ATTR_RW() macroses with coccinelle as they "generate" function names internally with "##". "fresh identifier" should really help here, but now I doubt it's required in device_attr_show.cocci, function prototype is enough. Thanks, Denis
