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List:       glibc-alpha
Subject:    Re: [PATCH v3] mips: dl-machine-reject-phdr: Get rid of alloca.
From:       Joe Simmons-Talbott via Libc-alpha <libc-alpha () sourceware ! org>
Date:       2023-08-30 12:29:35
Message-ID: 20230830122935.GE3849957 () oak
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On Wed, Aug 30, 2023 at 04:18:58PM +0800, Ying Huang wrote:
> Hi,
> 
> I have tested this patch on my lab, the resutls of make and make check all were good.
> 
> And make check did not introduce new XFAILS.
> 
> The environment is:
> 
> gcc 12.2.0, binutils 2.40, mips64el-linux-gnuabi64

Thank you for testing.  May I add a Tested-by: line?

Thanks,
Joe

> 
> 
> Thanks,
> 
> Ying
> 
> 
> 在 2023/8/30 03:30, Joe Simmons-Talbott via Libc-alpha 写道:
> > 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
> >>

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