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Message-ID: <09df9d75-13e7-45fe-89af-33fe118e797b@gmail.com>
Date: Sun, 12 Apr 2026 09:00:00 +0300
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User-Agent: Mozilla Thunderbird
Subject: Re: Non-compliant SASLprep implementation for ASCII characters
To: Michael Paquier <michael@paquier.xyz>,
 John Naylor <johncnaylorls@gmail.com>
Cc: Postgres hackers <pgsql-hackers@lists.postgresql.org>
References: <aaEJ-El2seZHeFcG@paquier.xyz>
 <CANWCAZbgyvx66qfngNvW0n+uEv3=Bak1X5GLPr4sZApuHDPV-g@mail.gmail.com>
 <abt60Gcc4drBlY1N@paquier.xyz>
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From: Alexander Lakhin <exclusion@gmail.com>
In-Reply-To: <abt60Gcc4drBlY1N@paquier.xyz>
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Hello Michael,

19.03.2026 06:25, Michael Paquier wrote:
> Applied the result for the module, to have at least the coverage part.
> The last piece is refreshed, and attached for now.
> --

When running make check for src/test/modules/test_saslprep under Valgrind,
I've discovered:
# --- /pgtest/postgresql.git/src/test/modules/test_saslprep/expected/test_saslprep.out 2026-04-12 07:44:47.090517505 +0300
# +++ /pgtest/postgresql.git/src/test/modules/test_saslprep/results/test_saslprep.out 2026-04-12 08:03:29.353348951 +0300
# @@ -2,151 +2,7 @@
#  CREATE EXTENSION test_saslprep;
#  -- Incomplete UTF-8 sequence.
#  SELECT test_saslprep('\xef');
# -  test_saslprep
# ------------------
# - (,INVALID_UTF8)
# -(1 row)
# -
...
-
-DROP EXTENSION test_saslprep;
+server closed the connection unexpectedly
+   This probably means the server terminated abnormally
+   before or while processing the request.
+connection to server was lost

src/test/modules/test_saslprep/log/postmaster.log
2026-04-12 08:03:26.064 EEST postmaster[1043298] LOG:  database system is ready to accept connections
2026-04-12 08:03:26.078 EEST dead-end client backend[1043325] [unknown] FATAL:  the database system is starting up
==00:00:00:04.413 1043360== Invalid read of size 1
==00:00:00:04.413 1043360==    at 0x484F234: strlen (in /usr/libexec/valgrind/vgpreload_memcheck-amd64-linux.so)
==00:00:00:04.413 1043360==    by 0x5277C6F: strlcpy (strlcpy.c:24)
==00:00:00:04.413 1043360==    by 0x48648CF: test_saslprep (test_saslprep.c:87)
==00:00:00:04.413 1043360==    by 0x541A45: ExecInterpExpr (execExprInterp.c:979)
==00:00:00:04.413 1043360==    by 0x5446A1: ExecInterpExprStillValid (execExprInterp.c:2301)
==00:00:00:04.413 1043360==    by 0x5AD1FD: ExecEvalExprNoReturn (executor.h:433)
==00:00:00:04.413 1043360==    by 0x5AD2BB: ExecEvalExprNoReturnSwitchContext (executor.h:474)
==00:00:00:04.413 1043360==    by 0x5AD31C: ExecProject (executor.h:506)
==00:00:00:04.413 1043360==    by 0x5AD53F: ExecResult (nodeResult.c:135)
==00:00:00:04.413 1043360==    by 0x55F5E4: ExecProcNodeFirst (execProcnode.c:469)
==00:00:00:04.413 1043360==    by 0x55108F: ExecProcNode (executor.h:327)
==00:00:00:04.413 1043360==    by 0x554149: ExecutePlan (execMain.c:1736)
==00:00:00:04.413 1043360==  Address 0x7439295 is 6,917 bytes inside a block of size 8,192 alloc'd
==00:00:00:04.413 1043360==    at 0x4846828: malloc (in /usr/libexec/valgrind/vgpreload_memcheck-amd64-linux.so)
==00:00:00:04.413 1043360==    by 0xADBE27: AllocSetContextCreateInternal (aset.c:444)
==00:00:00:04.413 1043360==    by 0x762E31: PostmasterMain (postmaster.c:534)
==00:00:00:04.413 1043360==    by 0x5E9543: main (main.c:231)
==00:00:00:04.413 1043360==
...
==00:00:00:04.413 1043360==
==00:00:00:04.414 1043360== Exit program on first error (--exit-on-first-error=yes)
2026-04-12 08:03:29.349 EEST postmaster[1043298] LOG:  client backend (PID 1043360) exited with exit code 1
2026-04-12 08:03:29.349 EEST postmaster[1043298] DETAIL:  Failed process was running: SELECT test_saslprep('\xef');

The corresponding code:
     src_len = VARSIZE_ANY_EXHDR(string);
     src = VARDATA_ANY(string);

     /*
      * Copy the input given, to make SASLprep() act on a sanitized string.
      */
     input_data = palloc0(src_len + 1);
     strlcpy(input_data, src, src_len + 1);

That is, strlcpy() tries to evaluate strlen() for src, which contains only
one byte without null terminator.

skink tests this module successfully [1] by some reason:
================================== 151/394 ===================================
test:         test_saslprep - postgresql:test_saslprep/regress
start time:   13:26:00
duration:     8.04s
result:       exit status 0
command:      ...
----------------------------------- stdout -----------------------------------
# executing test in /home/bf/bf-build/skink-master/HEAD/pgsql.build/testrun/test_saslprep/regress group test_saslprep 
test regress
# initializing database system by copying initdb template
# using temp instance on port 40096 with PID 3982971
ok 1         - test_saslprep                            1971 ms
1..1
# All 1 tests passed.
# test succeeded

[1] https://buildfarm.postgresql.org/cgi-bin/show_stage_log.pl?nm=skink&dt=2026-04-11%2011%3A31%3A01&stg=misc-check

Best regards,
Alexander
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    <div class="moz-cite-prefix">Hello Michael,<br>
      <br>
      19.03.2026 06:25, Michael Paquier wrote:<br>
    </div>
    <blockquote type="cite" cite="mid:abt60Gcc4drBlY1N@paquier.xyz">
      <pre wrap="" class="moz-quote-pre">Applied the result for the module, to have at least the coverage part.
The last piece is refreshed, and attached for now.
--
</pre>
    </blockquote>
    <br>
    When running make check for src/test/modules/test_saslprep under
    Valgrind,<br>
    I've discovered:<br>
    # ---
/pgtest/postgresql.git/src/test/modules/test_saslprep/expected/test_saslprep.out 
    2026-04-12 07:44:47.090517505 +0300<br>
    # +++
/pgtest/postgresql.git/src/test/modules/test_saslprep/results/test_saslprep.out  
    2026-04-12 08:03:29.353348951 +0300<br>
    # @@ -2,151 +2,7 @@<br>
    #  CREATE EXTENSION test_saslprep;<br>
    #  -- Incomplete UTF-8 sequence.<br>
    #  SELECT test_saslprep('\xef');<br>
    # -  test_saslprep  <br>
    # ------------------<br>
    # - (,INVALID_UTF8)<br>
    # -(1 row)<br>
    # -<br>
    ...<br>
    -<br>
    -DROP EXTENSION test_saslprep;<br>
    +server closed the connection unexpectedly<br>
    +   This probably means the server terminated abnormally<br>
    +   before or while processing the request.<br>
    +connection to server was lost<br>
    <br>
    src/test/modules/test_saslprep/log/postmaster.log<br>
    2026-04-12 08:03:26.064 EEST postmaster[1043298] LOG:  database
    system is ready to accept connections<br>
    2026-04-12 08:03:26.078 EEST dead-end client backend[1043325]
    [unknown] FATAL:  the database system is starting up<br>
    ==00:00:00:04.413 1043360== Invalid read of size 1<br>
    ==00:00:00:04.413 1043360==    at 0x484F234: strlen (in
    /usr/libexec/valgrind/vgpreload_memcheck-amd64-linux.so)<br>
    ==00:00:00:04.413 1043360==    by 0x5277C6F: strlcpy (strlcpy.c:24)<br>
    ==00:00:00:04.413 1043360==    by 0x48648CF: test_saslprep
    (test_saslprep.c:87)<br>
    ==00:00:00:04.413 1043360==    by 0x541A45: ExecInterpExpr
    (execExprInterp.c:979)<br>
    ==00:00:00:04.413 1043360==    by 0x5446A1: ExecInterpExprStillValid
    (execExprInterp.c:2301)<br>
    ==00:00:00:04.413 1043360==    by 0x5AD1FD: ExecEvalExprNoReturn
    (executor.h:433)<br>
    ==00:00:00:04.413 1043360==    by 0x5AD2BB:
    ExecEvalExprNoReturnSwitchContext (executor.h:474)<br>
    ==00:00:00:04.413 1043360==    by 0x5AD31C: ExecProject
    (executor.h:506)<br>
    ==00:00:00:04.413 1043360==    by 0x5AD53F: ExecResult
    (nodeResult.c:135)<br>
    ==00:00:00:04.413 1043360==    by 0x55F5E4: ExecProcNodeFirst
    (execProcnode.c:469)<br>
    ==00:00:00:04.413 1043360==    by 0x55108F: ExecProcNode
    (executor.h:327)<br>
    ==00:00:00:04.413 1043360==    by 0x554149: ExecutePlan
    (execMain.c:1736)<br>
    ==00:00:00:04.413 1043360==  Address 0x7439295 is 6,917 bytes inside
    a block of size 8,192 alloc'd<br>
    ==00:00:00:04.413 1043360==    at 0x4846828: malloc (in
    /usr/libexec/valgrind/vgpreload_memcheck-amd64-linux.so)<br>
    ==00:00:00:04.413 1043360==    by 0xADBE27:
    AllocSetContextCreateInternal (aset.c:444)<br>
    ==00:00:00:04.413 1043360==    by 0x762E31: PostmasterMain
    (postmaster.c:534)<br>
    ==00:00:00:04.413 1043360==    by 0x5E9543: main (main.c:231)<br>
    ==00:00:00:04.413 1043360==<br>
    ...<br>
    ==00:00:00:04.413 1043360==<br>
    ==00:00:00:04.414 1043360== Exit program on first error
    (--exit-on-first-error=yes)<br>
    2026-04-12 08:03:29.349 EEST postmaster[1043298] LOG:  client
    backend (PID 1043360) exited with exit code 1<br>
    2026-04-12 08:03:29.349 EEST postmaster[1043298] DETAIL:  Failed
    process was running: SELECT test_saslprep('\xef');<br>
    <br>
    The corresponding code:<br>
        src_len = VARSIZE_ANY_EXHDR(string);<br>
        src = VARDATA_ANY(string);<br>
    <br>
        /*<br>
         * Copy the input given, to make SASLprep() act on a sanitized
    string.<br>
         */<br>
        input_data = palloc0(src_len + 1);<br>
        strlcpy(input_data, src, src_len + 1);<br>
    <br>
    That is, strlcpy() tries to evaluate strlen() for src, which
    contains only<br>
    one byte without null terminator.<br>
    <br>
    skink tests this module successfully [1] by some reason:<br>
    ================================== 151/394
    ===================================<br>
    test:         test_saslprep - postgresql:test_saslprep/regress<br>
    start time:   13:26:00<br>
    duration:     8.04s<br>
    result:       exit status 0<br>
    command:      ...<br>
    ----------------------------------- stdout
    -----------------------------------<br>
    # executing test in
/home/bf/bf-build/skink-master/HEAD/pgsql.build/testrun/test_saslprep/regress
    group test_saslprep test regress<br>
    # initializing database system by copying initdb template<br>
    # using temp instance on port 40096 with PID 3982971<br>
    ok 1         - test_saslprep                            1971 ms<br>
    1..1<br>
    # All 1 tests passed.<br>
    # test succeeded<br>
    <br>
    [1]
<a class="moz-txt-link-freetext" href="https://buildfarm.postgresql.org/cgi-bin/show_stage_log.pl?nm=skink&amp;dt=2026-04-11%2011%3A31%3A01&amp;stg=misc-check">https://buildfarm.postgresql.org/cgi-bin/show_stage_log.pl?nm=skink&amp;dt=2026-04-11%2011%3A31%3A01&amp;stg=misc-check</a><br>
    <br>
    Best regards,<br>
    Alexander<br>
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