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Re: [PATCH] Fix delta integer overflows

From
Junio C Hamano <gitster@pobox.com>
Date
Aug 8, 2017, 01:44 UTC
Message-ID
<xmqqvalyn89b.fsf@gitster.mtv.corp.google.com>
In-Reply-To
<xmqq1sonql76.fsf@gitster.mtv.corp.google.com>
Junio C Hamano <gitster@pobox.com> writes:
Show 26 quoted lines
> Martin Koegler <martin.koegler@chello.at> writes:
>
>> From: Martin Koegler <martin.koegler@chello.at>
>>
>> The current delta code produces incorrect pack objects for files > 4GB.
>>
>> Signed-off-by: Martin Koegler <martin.koegler@chello.at>
>> ---
>>  diff-delta.c | 23 ++++++++++++-----------
>>  1 file changed, 12 insertions(+), 11 deletions(-)
>>
>> Just pass any file > 4 GB to the delta-compression [by increasing the delta limits].
>> As file size, a truncated 32bit value will be encoded, leading to broken pack files.
>
> The patch obviously makes the code better and self consistent in
> that "struct delta_index" has src_size as ulong, and this function
> takes trg_size as ulong, and it was plain wrong for the code to
> assume that "i", which is uint, can receive it safely.
>
> In the longer term we might want to move to size_t or even
> uintmax_t, as the ulong on a platform may not be long enough in
> order to express the largest file size the platform can have, but
> this patch (1) is good even without such a change, and (2) gives a
> good foundation to build on if we want such a change on top.
>
> Thanks.  Will queue.

Having said that, I am a bit curious how you came to this patch. Was the issue found by code inspection, or did you actually have a real life use case to raise the core.bigFileThreshold configuration to a value above 4GB?

Thanks.
Previous: Johannes SchindelinNext: Martin Koegler
Message 10 of 11 in “Fix delta integer overflows”
  1. Fix delta integer overflowsMartin Koegler, Aug 7, 2017
  2. Junio C HamanoAug 7, 2017
  3. Johannes SchindelinAug 7, 2017
  4. Junio C HamanoAug 7, 2017
  5. Johannes SchindelinAug 7, 2017
  6. Junio C HamanoAug 7, 2017
  7. Junio C HamanoAug 7, 2017
  8. Martin KoeglerAug 8, 2017
  9. Johannes SchindelinAug 8, 2017
  10. Junio C HamanoAug 8, 2017
  11. Martin KoeglerAug 8, 2017

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