Re: [PATCH] Fix stringop-overflow errors from gcc 10 in iconv.

[Stefan Liebler <stli@linux.ibm.com>]

ping

On 6/16/20 2:24 PM, Stefan Liebler 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
>