[SSSD] [PATCHES] Enable printf format string checking

Jakub Hrozek jhrozek at redhat.com
Wed Sep 11 17:47:01 UTC 2013


On Wed, Sep 11, 2013 at 07:37:29PM +0200, Jakub Hrozek wrote:
> On Wed, Sep 11, 2013 at 04:57:57PM +0200, Lukas Slebodnik wrote:
> > On (10/09/13 17:12), Jakub Hrozek wrote:
> > >On Wed, Sep 04, 2013 at 06:34:52PM +0200, Lukas Slebodnik wrote:
> > >> On (03/09/13 00:25), Jakub Hrozek wrote:
> > >> >On Wed, Aug 21, 2013 at 03:35:11PM +0200, Lukas Slebodnik wrote:
> > >> >> On (21/08/13 13:46), Jakub Hrozek wrote:
> > >> >> >Sorry it took so long before we got to another review of the patch. The
> > >> >> >ticket is targeted for 1.12 so initially I was thinking of the patchset
> > >> >> >as lower priority than the other work.
> > >> >> >
> > >> >> >On Wed, Jul 24, 2013 at 10:32:29AM +0200, Lukas Slebodnik wrote:
> > >> >> >> On (24/07/13 09:41), Ondrej Kos wrote:
> > >> >> >> >On 07/23/2013 06:21 PM, Lukas Slebodnik wrote:
> > >> >> >> >>ehlo,
> > >> >> >> >>
> > >> >> >> >>It would be great to have enabled printf format string checking in RHEL7.
> > >> >> >> >>Therefore I decided to send pateches for ticket
> > >> >> >> >>https://fedorahosted.org/sssd/ticket/1945
> > >> >> >> >>
> > >> >> >> >>Patch 0001 -- Even if this patch is first, it should be applied in upstream as
> > >> >> >> >>          last.
> > >> >> >
> > >> >> >              ^^^^ Does it matter? I'll apply the whole set anyway..
> > >> >> It can make a big noise in case of bisecting.
> > >> >> I moved this patch to the end.
> > >> >
> > >> >Thanks. I'll try to remember to ask someone to double-check before pushing
> > >> >:-)
> > >> >
> > >> >> 
> > >> >> >
> > >> >> >Some comments below..
> > >> >> >
> > >> >> >> >>
> > >> >> >> >>Patch 0002 - 0006 -- trivial
> > >> >> >> >>Patch 0007 -- ssize_t is not defined in ANSI c99, IIRC it is defined in posix
> > >> >> >> >>               as a signed type, therefore format should be used "zd"
> > >> >> >> >>Patch 0008 -- size_t is defined in ANSI c99 as unzigned type -> "zu"
> > >> >> >
> > >> >> >btw size_t seems to be part of standard library, not the language
> > >> >> >specification per se. Not that it matters for the patch :)
> > >> >> size_t can be part of standard library, but ANSI c99 says size_t is unsigned
> > >> >> type.
> > >> >> 
> > >> >> Problem is that sizeof(size_t) is different on 32-bit platform and 64-bit
> > >> >> platform
> > >> >
> > >> >OK
> > >> >
> > >> >> 
> > >> >> >
> > >> >> >> >>Patch 0009 -- wrapper for inttypes.h and for future format macros.
> > >> >> >> >>Patch 0012 -- formating types defined in stdint.h uint_32_t ...
> > >> >> >> >>            -- there are used macros defined in inttypes.h
> > >> >> >> >>Patches 0010 - 0015 fix formating for special variables (key_serial_t, rlim_t...)
> > >> >> >> >>                     and for some types I created macros in sss_format.h
> > >> >> >> >>Patch 0010 -- key_serial_t is typedef of int32_t, but it could be defined
> > >> >> >> >>          differently in another (platforms/ implemantations of kerberos)
> > >> >> >> >>Patch 0011 -- it seems that rlim_t us the same as uint64_t, but it was defined
> > >> >> >> >>            using conditional build an not a typedef of std types.
> > >> >> >> >>Patch 0013 -- time_t is defined as "long int" sizeof_i386(time_t) != sizeof_x86_64(time_t)
> > >> >> >> >>Patch 0014 -- ber_int and ber_tag are typedef for int and unsigned long
> > >> >> >> >>Patch 0015 -- gid_t and uid_t are typedef as unsigned
> > >> >> >> >>               (I checked linux 32 bit, linu 64_bit and freebsd 64 bit)
> > >> >> >
> > >> >> >Actually /usr/include/bits/typesizes.h says:
> > >> >> >#define __UID_T_TYPE            __U32_TYPE
> > >> >> and you forgot to add:
> > >> >> shell$ grep -RniI __U32_TYPE
> > >> >> bits/types.h:101:#define __U32_TYPE             unsigned int
> > >> >
> > >> >I think this is lucky coincidence where unsigned int is 32bits wide.
> > >> >
> > >> >But to be honest I haven't found any information that would state that
> > >> >uid_t or gid_t is guaranteed to be 32bit (even though some places in the
> > >> >SSSD rely on uid_t == uint32_t). As far as I can see, POSIX simply says
> > >> >that both are opaque numeric types. Too bad the system headers don't
> > >> >provide some kind of format specifier..
> > >> >
> > >> >I wonder if we should check the width during configure and define our
> > >> >own specifier based on what we discover?
> > >> >
> > >> >> 
> > >> >> >
> > >> >> >(and then defines __UID_T_TYPE to __uid_t which in turn gets typedefed to uid_t)
> > >> >> >
> > >> >
> > >> >[snip]
> > >> >
> > >> >> >> Subject: [PATCH 10/16] Fix formating of variables with type: key_serial_t
> > >> >> >> Subject: [PATCH 11/16] Fix formating of variables with type: rlim_t
> > >> >> >> Subject: [PATCH 12/16] Fix formating of variables with type defined in stdint.h
> > >> >> >
> > >> >> >Nice, I didn't know these existed. But to be honest, these format specifiers
> > >> >> >seem ugly to me..wouldn't it be nicer to cast the variables to a larger type
> > >> >> >(long or unsigned long) and then use plan C conversion?
> > >> >> I agree with Stephen casting is not very portable.
> > >> >> Some platforms needn't have defned long long unsigend or there can be another
> > >> >> type which is bigger.
> > >> >> 
> > >> >> uintmax_t/intmax_t could be used as the larget type.
> > >> >> In this case modifier "j" should be used
> > >> >>     format_fun("%jd %ju\n" (uintmax_t) uint_8_var, (intmax_t)int8_t_var)
> > >> >> but it is overkill to cast uint_8_var to 64_vit variable (or in future 128 bit:-)
> > >> >> 
> > >> >> And last point. I don't like casting of argumets in formating functions.
> > >> >> 
> > >> >> ------------------
> > >> >> "man inttypes.h" is very helpful
> > >> >> ------------------
> > >> >
> > >> >OK, I'm convinced :-)
> > >> >
> > >> >> 
> > >> >> >> Subject: [PATCH 13/16] Fix formating of variables with type: time_t
> > >> >> >I think this is OK, my C reference says that time_t can be of "any arithmetic
> > >> >> >type" but also states that long is traditionally used.
> > >> >> >
> > >> >> >> Subject: [PATCH 14/16] Fix formating of variables with ber_ type
> > >> >> >ACK
> > >> >> >
> > >> >> >> Subject: [PATCH 15/16] Fix formating of variables with type: [gu]?id_t
> > >> >> >
> > >> >> >This is the main point of discussion in the patchset I think. IIRC POSIX
> > >> >> >states that IDs are 32bit unsigned integers. That's precisely why we have
> > >> >> >casted them up to unsigned (long) long. Did you see warnings with some
> > >> >> >strict combination of CFLAGS?
> > >> >> >
> > >> >> -Wformat is automatically  enabled by -Wall, There is no problem with CFLAGS.
> > >> >> You can try to revert this patch (or do not apply this patch)
> > >> >> And warnings will appear. clang gives more hints.
> > >> >> 
> > >> >> But it is possibel to add another macro to header file sss_format.h
> > >> >> 
> > >> >> >> Subject: [PATCH 16/16] Fix warning: data argument not used by format string
> > >> >> >Oof, these are bad. Thank you. ACK.
> > >> >> Those fixes are not critical, only unsufficient information will be printed.
> > >> >> 
> > >> >> Updated patches are attached.
> > >> >> 
> > >> >> LS
> > >> >
> > >> >Sorry the review has stalled for a bit. I think that once we resolve the
> > >> >uid_t patch, we can push the whole patchset.
> > >> 
> > >> I added 3 new macros for formating [ug]?id types: PRIid, PRIgid, PRIuid
> > >
> > >I like this approach. I just wonder if we should namespace these to say
> > >SPRI instead? Would it be too much work or doable with a
> > >search-and-replace?
> > >
> > >> 
> > >> BTW: I rebased patches and spot 3 new warnings :-)
> > >> 
> > >
> > >Yeah, we really need to push these patches..
> > >
> > >> index efaa247dd22d2ae100e8881c010dfe26a9a10cca..5f2465ca6d8aef7fc486a033e7d3759050c0dec8 100644
> > >> --- a/src/providers/ldap/sdap_async_initgroups_ad.c
> > >> +++ b/src/providers/ldap/sdap_async_initgroups_ad.c
> > >> @@ -472,7 +472,7 @@ sdap_get_ad_tokengroups_initgroups_lookup_done(struct tevent_req *subreq)
> > >>          }
> > >>  
> > >>          DEBUG(SSSDBG_TRACE_LIBS,
> > >> -              ("Processing membership GID [%lu]\n",
> > >> +              ("Processing membership GID [%u]\n",
> > >>                 gid));
> > >>  
> > >
> > >This change is overwritten in a later patch.
> > >
> > >I couldn't apply patches 7 and 16, can you rebase?
> > 
> > Attached patches are rebased on top of current master.
> > 
> > All macros from sss_format.h were renamed from PRI -> SPRI
> > 
> > LS
> 
> These patches work for me.
> 
> ACK

Pushed all to master. Great work!



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