This is the mail archive of the libc-alpha@sourceware.org mailing list for the glibc project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: [PATCH v2] locale: don't crash if locale-archive contains all zeros


On Tue, Dec 03, 2013 at 12:40:54PM +0100, OndÅej BÃlka wrote:
> On Tue, Dec 03, 2013 at 12:21:33PM +0100, Andreas Schwab wrote:
> > Aurelien Jarno <aurelien@aurel32.net> writes:
> > 
> > > diff --git a/locale/loadarchive.c b/locale/loadarchive.c
> > > index 70136dc..f723780 100644
> > > --- a/locale/loadarchive.c
> > > +++ b/locale/loadarchive.c
> > > @@ -274,6 +274,10 @@ _nl_load_locale_from_archive (int category, const char **namep)
> > >    namehashtab = (struct namehashent *) ((char *) head
> > >  					+ head->namehash_offset);
> > >  
> > > +  /* Avoid division by 0 if the file is corrupted.  */
> > > +  if (__glibc_unlikely (head->namehash_size == 0))
> > > +    goto close_and_out;
> > > +
> > >    idx = hval % head->namehash_size;
> > >    incr = 1 + hval % (head->namehash_size - 2);
> > 
> > That won't help for head->namehash_size == 2, or any other corruptions.

Indeed it will still crash for head->namehash_size == 2, it's something
I missed. For other corruptions, they are handled later in the code.

> Which is less common zeroed file. Proper solution would be starting
> files with magic constant which is too late to add.

Isn't it possible to break the format between releases, iow people are
not supposed to rebuild the locales when installing a new libc?

> Do you have idea to detect corruption other than changing check to
> 
> head->namehash_size == 0 || head->namehash_size == 2

I don't think 1 is a value that can be used in practice, so what about 
head->namehash_size <= 2 ?

-- 
Aurelien Jarno	                        GPG: 1024D/F1BCDB73
aurelien@aurel32.net                 http://www.aurel32.net


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]