Horton

Re: glibc qsort() vulnerability

Thomas Munro <thomas.munro@gmail.com>

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From: Thomas Munro <thomas.munro@gmail.com>
To: Andres Freund <andres@anarazel.de>
Cc: Nathan Bossart <nathandbossart@gmail.com>, Heikki Linnakangas <hlinnaka@iki.fi>, Mats Kindahl <mats@timescale.com>, Tom Lane <tgl@sss.pgh.pa.us>, pgsql-hackers@lists.postgresql.org
Date: 2024-02-08T02:38:10Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Use new overflow-safe integer comparison functions.

  2. Introduce overflow-safe integer comparison functions.

  3. Replace calls to pg_qsort() with the qsort() macro.

  4. Switch over to using our own qsort() all the time, as has been proposed

On Thu, Feb 8, 2024 at 3:06 PM Andres Freund <andres@anarazel.de> wrote:
> On 2024-02-07 19:52:11 -0600, Nathan Bossart wrote:
> > On Wed, Feb 07, 2024 at 04:42:07PM -0800, Andres Freund wrote:
> > > On 2024-02-07 16:21:24 -0600, Nathan Bossart wrote:
> > >> The assembly for that looks encouraging, but I still need to actually test
> > >> it...
> > >
> > > Possible. For 16bit upcasting to 32bit is clearly the best way. For 32 bit
> > > that doesn't work, given the 32bit return, so we need something more.
> >
> > For the same compASC() test, I see an ~8.4% improvement with your int64
> > code
>
> Just to be clear, that code unfortuntely isn't correct, the return value is a
> 32 bit integer, so the 64bit difference doesn't help. In contrast to the 16bit
> case.

Perhaps you could wrap it in a branch-free sign() function so you get
a narrow answer?

https://stackoverflow.com/questions/14579920/fast-sign-of-integer-in-c