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.
next prev parent 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
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