On Wed, Jan 17, 2024 at 05:51:58AM +0300, Vladimir 'phcoder' Serbinenko wrote:
> On Tue, Jan 16, 2024 at 12:23 PM Gary Lin via Grub-devel
> <grub-devel@gnu.org> wrote:
> >
> > From: Daniel Axtens <d...@axtens.net>
> >
> > Do a few things to make libtasn1 compile as part of grub:
> >
> > - redefine _asn1_strcat. grub removed strcat so replace it with the
> > appropriate calls to memcpy and strlen. Use this internally where
> > strcat was used.
> >
> strcat is especially dangerous. If you can't easily replace it with
> strncat/strlcat, you probably have a buffer overflow or potential to
> have one after some code refactoring.strcpy isn't great either but a
> bit better. memcpy+strlen isn't a good replacement. Maybe we can
> upstream use of strncat, not based on GRUB needs but based on dangers
> of strcat.
I did a quick check of the use of strcat in libtasn1, and replacing
strcat with strncat looks doable since the length of the destination string
are given or can be calculated easily.
> > - replace c_isdigit with grub_isdigit (and don't import c-ctype from
> > gnulib) grub_isdigit provides the same functionality as c_isdigit: it
> > determines if the input is an ASCII digit without regard for locale.
> Can we add c-ctype.h into posix compat?
> >
Sure.
> > - replace GL_ATTRIBUTE_PURE with __attribute__((pure)) which been
> > supported since gcc-2.96. This avoids messing around with gnulib.
> >
> Why not add -DGL_ATTRIBUTE_PURE=... into cppflags? Or even to posix
> wrap as long as we're not in gnulib? (e.g. #ifndef GNULIB ... #endif)
Adding the cppflag looks an easy fix. Thanks for the suggestion.
> > - adjust libtasn1.h: drop the ASN1_API logic, it's not needed for our
> > modules. Unconditionally support const and pure attributes and adjust
> > header paths.
> Why not -DASN1_API= in cppflags?
> const/pure logic seems ok as it was. Did you encounter any problems?
I'm not sure about this part. Maybe Daniel had some problem with
ASN1_API.
> > if (dest_tot_size > dest_size)
> > {
> > - strncat (dest, src, (dest_tot_size - dest_size) - 1);
> > + memcpy (dest + dest_size, src, (dest_tot_size - dest_size) - 1);
>
> Please add strncat into posix wrap instead. This is a bad change.
>
Ok, will port strncat into posix wrap.
Thanks,
Gary Lin
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