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Re: Don't pass NULL pointer to strcmp().

Xing Guo <higuoxing@gmail.com>

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From: Xing Guo <higuoxing@gmail.com>
To: Aleksander Alekseev <aleksander@timescale.com>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>, Junwang Zhao <zhjwpku@gmail.com>
Date: 2023-11-01T13:03:10Z
Lists: pgsql-hackers

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Hi Aleksander and Junwang,

Thanks for your comments. I have updated the patch accordingly.

Best Regards,
Xing








On Wed, Nov 1, 2023 at 7:44 PM Aleksander Alekseev <aleksander@timescale.com>
wrote:

> Hi,
>
> > > I found that there's a nullable pointer being passed to strcmp() and
> > > can make the server crash. It can be reproduced on the latest master
> > > branch by crafting an extension[1]. Patch for fixing it is attatched.
> > >
> > > [1] https://github.com/higuoxing/guc_crash/tree/pg
>
> Thanks for reporting. I can confirm that the issue reproduces on the
> `master` branch and the proposed patch fixes it.
>
> > Can we set a string guc to NULL? If not, `*lconf->variable == NULL` would
> > be unnecessary.
>
> Judging by the rest of the code we better keep it, at least for consistenc.
>
> I see one more place with a similar code in guc.c around line 1472.
> Although I don't have exact steps to trigger a crash I suggest adding
> a similar check there.
>
> --
> Best regards,
> Aleksander Alekseev
>

Commits

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

  1. Make GetConfigOption/GetConfigOptionResetString return "" for NULL.

  2. Be more wary about NULL values for GUC string variables.

  3. doc: Replace reference to ERRCODE_RAISE_EXCEPTION by "raise_exception"