Horton

Re: ubsan

Alexander Law <exclusion@gmail.com>

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From: Alexander Lakhin <exclusion@gmail.com>
To: Andres Freund <andres@anarazel.de>, Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-hackers@postgresql.org
Date: 2023-09-27T11:00:00Z
Lists: pgsql-hackers 
Hello Andres,

22.11.2022 02:15, Andres Freund wrote:
> Hi,
>
> On 2022-09-29 18:17:55 -0700, Andres Freund wrote:
>> Attached is a rebased version of this patch. Hopefully with a reasonable
>> amount of comments?  I kind of wanted to add a comment to reached_main, but it
>> just seems to end up restating the variable name...
> I've now pushed a version of this with a few cleanups, mostly in
> .cirrus.yml.  It'll be interesting to see how many additional problems
> it finds via cfbot.

I've just discovered that that function __ubsan_default_options() is
incompatible with -fsanitize=hwaddress:
$ tmp_install/usr/local/pgsql/bin/postgres
Segmentation fault

Program received signal SIGSEGV, Segmentation fault.
0x000000555639e3ec in __hwasan_check_x0_0 ()
(gdb) bt
#0  0x000000555639e3ec in __hwasan_check_x0_0 ()
#1  0x000000555697b5a8 in __ubsan_default_options () at main.c:446
#2  0x0000005556367e48 in InitializeFlags ()
     at /home/builder/.termux-build/libllvm/src/compiler-rt/lib/hwasan/hwasan.cpp:133
#3  __hwasan_init () at /home/builder/.termux-build/libllvm/src/compiler-rt/lib/hwasan/hwasan.cpp:351
#4  0x0000007ff7f4929c in __dl__ZL13call_functionPKcPFviPPcS2_ES0_ () from /system/bin/linker64
#5  0x0000007ff7f4900c in __dl__ZL10call_arrayIPFviPPcS1_EEvPKcPT_mbS5_ () from /system/bin/linker64
#6  0x0000007ff7f45670 in __dl__ZL29__linker_init_post_relocationR19KernelArgumentBlockR6soinfo ()
    from /system/bin/linker64
#7  0x0000007ff7f449c8 in __dl___linker_init () from /system/bin/linker64
#8  0x0000007ff7f4b208 in __dl__start () from /system/bin/linker64

I use clang version 16.0.6, Target: aarch64-unknown-linux-android24.

With just 'return ""' in __ubsan_default_options(), I've managed to run
`make check` (there is also an issue with check_stack_depth(),
but that's another story)...

Best regards,
Alexander

Commits

  1. Avoid possible crash within libsanitizer.

  2. ci: Use -fsanitize=undefined,alignment,address in linux tasks

  3. Add workaround to make ubsan and ps_status.c compatible

  4. Don't try to translate NULL in GetConfigOptionByNum().

  5. Don't call fwrite() with len == 0 when writing out relcache init file.

  6. configure: check for dlsym instead of dlopen.

  7. Clean up assorted failures under clang's -fsanitize=undefined checks.