On Fri, 2020-12-25 at 14:13 -0800, Tom Rix wrote: > On 12/25/20 9:06 AM, Joe Perches wrote: > > On Fri, 2020-12-25 at 06:56 -0800, Tom Rix wrote: > > > On 12/24/20 2:39 PM, Joe Perches wrote: > > [] > > > > Kernel code doesn't use a signed char or short with %hx or %hu very > > > > often > > > > but in case you didn't already know, any signed char/short emitted with > > > > anything like %hx or %hu needs to be left alone as sign extension > > > > occurs so: > > > Yes, this would also effect checkpatch. > > Of course but checkpatch is stupid and doesn't know types > > so it just assumes that the type argument is not signed. > > > > In general, that's a reasonable but imperfect assumption. > > > > coccinelle could probably do this properly as it's a much > > better parser. clang-tidy should be able to as well. > > > Ok. > > But types not matching the format string is a larger problem. > > Has there been an effort to clean these up ?
Not really no. __printf already does a reasonable job for that. The biggest issue for format type mismatches is the %p<foo> extensions. __printf can only verify that the argument is a pointer, not necessarily the 'right' type of pointed to object. There are overflow possibilities like '"%*ph", len, pointer' where pointer may not have len bytes available and, for instance, mismatched uses of %pI4 and %pI6 where %pI4 expects a pointer to 4 bytes and %pI6 expects a pointer to 16 bytes. Anyway it's not that easy a problem to analyze.
