Re: Speed up ICU case conversion by using ucasemap_utf8To*()

From: Alexander Lakhin <exclusion(at)gmail(dot)com>
To: Jeff Davis <pgsql(at)j-davis(dot)com>, Andreas Karlsson <andreas(at)proxel(dot)se>, zengman <zengman(at)halodbtech(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Speed up ICU case conversion by using ucasemap_utf8To*()
Date: 2026-03-12 04:00:00
Message-ID: 96d80a47-f17f-42fa-82b1-2908efbd6541@gmail.com
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Hello Jeff,

07.01.2026 00:10, Jeff Davis wrote:
> Committed, thank you!

I've discovered that starting from c4ff35f10, the following query:
CREATE COLLATION c (provider = icu, locale = 'icu_something');

makes asan detect (maybe dubious, but still..) stack-buffer-overflow:
==21963==ERROR: AddressSanitizer: stack-buffer-overflow on address 0x7ffd386d4e63 at pc 0x650cd7972a76 bp 0x7ffd386d4e00
sp 0x7ffd386d45a8
...
Address 0x7ffd386d4e63 is located in stack of thread T0 at offset 67 in frame
    #0 0x650cd86962ef in foldcase_options (.../usr/local/pgsql/bin/postgres+0x12322ef) (BuildId:
e441a9634858193e7358e5901e7948606ff5b1b1)

  This frame has 2 object(s):
    [48, 52) 'status' (line 993)
    [64, 67) 'lang' (line 992) <== Memory access at offset 67 overflows this variable

I use a build made with:
CC=gcc-13 CPPFLAGS="-fsanitize=address" LDFLAGS="-fsanitize=address -static-libasan" ./configure --with-icu ...

Could you please have a look?

Best regards,
Alexander

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