[PATCH v3] mips: dl-machine-reject-phdr: Get rid of alloca.

[Joe Simmons-Talbott]

Ping.

On Thu, Sep 07, 2023 at 08:25:50AM -0400, Joe Simmons-Talbott wrote:
> Ping for review.
> 
> On Tue, Aug 29, 2023 at 03:30:19PM -0400, Joe Simmons-Talbott via Libc-alpha wrote:
> > Ping.
> > 
> > On Mon, Jun 26, 2023 at 09:16:21AM -0400, Joe Simmons-Talbott wrote:
> > > Read directly into the mips_abiflags struct rather than reading the
> > > entire segment and using alloca when the passed buffer is not big enough.
> > > 
> > > Checked with build-many-glibcs.py on mips-linux-gnu
> > > ---
> > > Changes to v2:
> > >   * Rather than use a scratch buffer use the mips_abiflags struct itself
> > >     for reading since we're now just reading that much data and not the
> > >     whole segment.
> > > 
> > >  sysdeps/mips/dl-machine-reject-phdr.h | 26 ++++++++++----------------
> > >  1 file changed, 10 insertions(+), 16 deletions(-)
> > > 
> > > diff --git a/sysdeps/mips/dl-machine-reject-phdr.h b/sysdeps/mips/dl-machine-reject-phdr.h
> > > index 104b590661..b784697fc1 100644
> > > --- a/sysdeps/mips/dl-machine-reject-phdr.h
> > > +++ b/sysdeps/mips/dl-machine-reject-phdr.h
> > > @@ -161,7 +161,7 @@ elf_machine_reject_phdr_p (const ElfW(Phdr) *phdr, unsigned int phnum,
> > >    Lmid_t nsid;
> > >    int in_abi = -1;
> > >    struct abi_req in_req;
> > > -  Elf_MIPS_ABIFlags_v0 *mips_abiflags = NULL;
> > > +  Elf_MIPS_ABIFlags_v0 mips_abiflags;
> > >    bool perfect_match = false;
> > >  #if _MIPS_SIM == _ABIO32
> > >    unsigned int cur_mode = -1;
> > > @@ -176,25 +176,19 @@ elf_machine_reject_phdr_p (const ElfW(Phdr) *phdr, unsigned int phnum,
> > >    /* Read the attributes section.  */
> > >    if (ph != NULL)
> > >      {
> > > -      ElfW(Addr) size = ph->p_filesz;
> > > +      ElfW(Addr) size = sizeof (Elf_MIPS_ABIFlags_v0);
> > >  
> > > -      if (ph->p_offset + size <= len)
> > > -	mips_abiflags = (Elf_MIPS_ABIFlags_v0 *) (buf + ph->p_offset);
> > > -      else
> > > -	{
> > > -	  mips_abiflags = alloca (size);
> > > -	  __lseek (fd, ph->p_offset, SEEK_SET);
> > > -	  if (__libc_read (fd, (void *) mips_abiflags, size) != size)
> > > -	    REJECT ("   unable to read PT_MIPS_ABIFLAGS\n");
> > > -	}
> > > -
> > > -      if (size < sizeof (Elf_MIPS_ABIFlags_v0))
> > > +      if (ph->p_filesz < size)
> > >  	REJECT ("   contains malformed PT_MIPS_ABIFLAGS\n");
> > >  
> > > -      if (__glibc_unlikely (mips_abiflags->flags2 != 0))
> > > -	REJECT ("   unknown MIPS.abiflags flags2: %u\n", mips_abiflags->flags2);
> > > +      __lseek (fd, ph->p_offset, SEEK_SET);
> > > +      if (__libc_read (fd, (void *) &mips_abiflags, size) != size)
> > > +	REJECT ("   unable to read PT_MIPS_ABIFLAGS\n");
> > > +
> > > +      if (__glibc_unlikely (mips_abiflags.flags2 != 0))
> > > +	REJECT ("   unknown MIPS.abiflags flags2: %u\n", mips_abiflags.flags2);
> > >  
> > > -      in_abi = mips_abiflags->fp_abi;
> > > +      in_abi = mips_abiflags.fp_abi;
> > >      }
> > >  
> > >    /* ANY is compatible with anything.  */
> > > -- 
> > > 2.39.2
> > > 
> > 
>