public inbox for libc-alpha@sourceware.org
 help / color / mirror / Atom feed
From: Carlos O'Donell <carlos@redhat.com>
To: Stefan Liebler <stli@linux.ibm.com>, libc-alpha@sourceware.org
Subject: Re: [PATCH] Fix stringop-overflow errors from gcc 10 in iconv.
Date: Mon, 6 Jul 2020 11:03:04 -0400	[thread overview]
Message-ID: <42e031ef-2fd0-845a-4469-4d150e0608bf@redhat.com> (raw)
In-Reply-To: <a95277d4-c5b9-432c-2708-67bb31809d29@linux.ibm.com>

On 7/6/20 10:30 AM, Stefan Liebler wrote:
> On 6/26/20 8:00 PM, Matheus Castanho wrote:
>> Hi Stefan,
>>
>> On 6/16/20 9:24 AM, Stefan Liebler via Libc-alpha wrote:
>>> On s390x, I've recognize various -Werror=stringop-overflow messages
>>> in iconv/loop.c and iconv/skeleton.c if build with gcc10 -O3.
>>>
>>> With this commit gcc knows the size and do not raise those errors anymore.
>>> ---
>>>  iconv/loop.c     | 14 ++++++++------
>>>  iconv/skeleton.c |  8 +++++---
>>>  2 files changed, 13 insertions(+), 9 deletions(-)
>>>
>>> diff --git a/iconv/loop.c b/iconv/loop.c
>>> index 9f7570d591..b032fcd9ac 100644
>>> --- a/iconv/loop.c
>>> +++ b/iconv/loop.c
>>> @@ -420,8 +420,10 @@ SINGLE(LOOPFCT) (struct __gconv_step *step,
>>>  #  else
>>>        /* We don't have enough input for another complete input
>>>  	 character.  */
>>> -      while (inptr < inend)
>>> -	state->__value.__wchb[inlen++] = *inptr++;
>>> +      size_t inlen_after = inlen + (inend - inptr);
>>> +      assert (inlen_after <= sizeof (state->__value.__wchb));
>>> +      for (; inlen < inlen_after; inlen++)
>>> +	state->__value.__wchb[inlen] = *inptr++;
>>>  #  endif
>>>  
>>>        return __GCONV_INCOMPLETE_INPUT;
>>> @@ -483,11 +485,11 @@ SINGLE(LOOPFCT) (struct __gconv_step *step,
>>>        /* We don't have enough input for another complete input
>>>  	 character.  */
>>>        assert (inend - inptr > (state->__count & ~7));
>>> -      assert (inend - inptr <= sizeof (state->__value));
>>> +      assert (inend - inptr <= sizeof (state->__value.__wchb));
>>>        state->__count = (state->__count & ~7) | (inend - inptr);
>>> -      inlen = 0;
>>> -      while (inptr < inend)
>>> -	state->__value.__wchb[inlen++] = *inptr++;
>>> +      for (inlen = 0; inlen < inend - inptr; inlen++)
>>> +	state->__value.__wchb[inlen] = inptr[inlen];
>>> +      inptr = inend;
>>>  #  endif
>>>      }
>>>  
>>> diff --git a/iconv/skeleton.c b/iconv/skeleton.c
>>> index 1dc642e2fc..1a38b51a5a 100644
>>> --- a/iconv/skeleton.c
>>> +++ b/iconv/skeleton.c
>>> @@ -795,11 +795,13 @@ FUNCTION_NAME (struct __gconv_step *step, struct __gconv_step_data *data,
>>>  # else
>>>  	  /* Make sure the remaining bytes fit into the state objects
>>>  	     buffer.  */
>>> -	  assert (inend - *inptrp < 4);
>>> +	  size_t cnt_after = inend - *inptrp;
>>> +	  assert (cnt_after <= sizeof (data->__statep->__value.__wchb));
>>>  
>>>  	  size_t cnt;
>>> -	  for (cnt = 0; *inptrp < inend; ++cnt)
>>> -	    data->__statep->__value.__wchb[cnt] = *(*inptrp)++;
>>> +	  for (cnt = 0; cnt < cnt_after; ++cnt)
>>> +	    data->__statep->__value.__wchb[cnt] = (*inptrp)[cnt];
>>> +	  *inptrp = inend;
>>>  	  data->__statep->__count &= ~7;
>>>  	  data->__statep->__count |= cnt;
>>>  # endif
>>>
>>
>>
>> Thanks for working on this! I also noticed this same issue on power.
>> This patch indeed fixes it there as well.
>>
>> As for the patch, I'm not that familiar with iconv code, but by checking
>> the modified snippet, the loops seem equivalent and the pointers are
>> properly modified as before. So it's mostly harmless, basically
>> rewriting those lines in a different way to please GCC.
>>
>> LGTM.
>>
>> --
>> Matheus Castanho
>>
> 
> @Carlos: Is this patch okay to commit before the release?

Yes, this doesn't change ABI/API and fixes compiles with gcc 10.

It is not subject to the ABI/API freeze currently in effect.

Please do continue to fix bugs and enable operation with the
latest released upstream toolchains.

-- 
Cheers,
Carlos.


  reply	other threads:[~2020-07-06 15:03 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-16 12:24 Stefan Liebler
2020-06-26  7:52 ` Stefan Liebler
2020-06-26 18:00 ` Matheus Castanho
2020-07-06 14:30   ` Stefan Liebler
2020-07-06 15:03     ` Carlos O'Donell [this message]
2020-07-07  7:44       ` Stefan Liebler

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=42e031ef-2fd0-845a-4469-4d150e0608bf@redhat.com \
    --to=carlos@redhat.com \
    --cc=libc-alpha@sourceware.org \
    --cc=stli@linux.ibm.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).