Re: Fix some ubsan/asan related issues

Hello,

30.01.2024 18:57, Tristan Partin wrote:
> Patch 1:
>
> Passing NULL as a second argument to memcpy breaks ubsan, ...

Maybe you would like to fix also one more similar place, reached with:
create extension xml2;
select xslt_process('<x/>',
$$<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:template match="@*|node()">
</xsl:template>
</xsl:stylesheet>$$);

varlena.c:201:26: runtime error: null pointer passed as argument 2, which is declared to never be null

There is also an issue with pg_bsd_indent, I stumble upon when doing
`make check-world` with the sanitizers enabled:
https://www.postgresql.org/message-id/591971ce-25c1-90f3-0526-5f54e3ebb32e%40gmail.com

31.01.2024 00:23, Andres Freund wrote:
> The reason asan fails is that it uses a "shadow stack" to track stack variable
> lifetimes. These confuse our stack depth check. CI doesn't have the issue
> because the compiler doesn't yet enable the feature, locally I get around it
> by using ASAN_OPTIONS=detect_stack_use_after_return=0:...

Even with detect_stack_use_after_return=0, clang-18's asan makes the test
012_subtransactions.pl fail:
2024-01-31 03:24:25.691 UTC [4112455] 012_subtransactions.pl LOG: statement: SELECT hs_subxids(201);
2024-01-31 03:24:25.714 UTC [4112455] 012_subtransactions.pl ERROR: stack depth limit exceeded
2024-01-31 03:24:25.714 UTC [4112455] 012_subtransactions.pl HINT: Increase the configuration parameter max_stack_depth 
(currently 2048kB), after ensuring the platform's stack depth limit is adequate.

(All the other tests pass.)
Though the same test passes when I use clang-16.

Best regards,
Alexander