Re: Code quality issues in ICU patch

On Fri, Jun 23, 2017 at 12:31:40PM -0400, Tom Lane wrote:
> icu_to_uchar() and icu_from_uchar(), and perhaps other places, are
> touchingly naive about integer overflow hazards in buffer size
> calculations. I call particular attention to this bit in
> icu_from_uchar():
>
> len_result = UCNV_GET_MAX_BYTES_FOR_STRING(len_uchar, ucnv_getMaxCharSize(icu_converter));
>
> The ICU man pages say that that macro is defined as
>
> #define UCNV_GET_MAX_BYTES_FOR_STRING(length, maxCharSize) (((int32_t)(length)+10)*(int32_t)(maxCharSize))
>
> which means that getting this to overflow (resulting in
> probably-exploitable memory overruns) would be about as hard as
> taking candy from a baby.

So it kicks off really loud and persistent alarms, and isn't as easy
as you thought, even taking this into account?

Best,
David.
--
David Fetter <david(at)fetter(dot)org> http://fetter.org/
Phone: +1 415 235 3778 AIM: dfetter666 Yahoo!: dfetter
Skype: davidfetter XMPP: david(dot)fetter(at)gmail(dot)com

Remember to vote!
Consider donating to Postgres: http://www.postgresql.org/about/donate