On Fri, Mar 07, 2025 at 12:03:47AM +0100, Tomas Vondra wrote:
> while running check-world on 64-bit arm (rpi5 with Debian 12.9), I got a
> couple reports like this:
>
> ==64550== Use of uninitialised value of size 8
> ==64550== at 0xA62FE0: wrapper_handler (pqsignal.c:107)
> ==64550== by 0x580BB9E7: ??? (in
> /usr/libexec/valgrind/memcheck-arm64-linux)
> ==64550== Uninitialised value was created by a stack allocation
> ==64550== at 0x4F94660: strcoll_l (strcoll_l.c:258)
> ==64550==
> {
> <insert_a_suppression_name_here>
> Memcheck:Value8
> fun:wrapper_handler
> obj:/usr/libexec/valgrind/memcheck-arm64-linux
> }
> **64550** Valgrind detected 1 error(s) during execution of "ANALYZE
> mcv_lists;"
>
> The exact command varies, I don't think it's necessarily about analyze
> or extended stats.
>
> The line the report refers to is this:
>
> (*pqsignal_handlers[postgres_signal_arg]) (postgres_signal_arg);
>
> so I guess it can't be about postgres_signal_arg (as that's an int). But
> that leaves just pqsignal_handlers, and why would that be uninitialized?
>
> The closest thing I found in archives is [1] from about a year ago, but
> we haven't found any clear explanation there either :-(
Hm. The pointer to strcoll_l makes me wonder if there might be an issue in
one of the handler functions that wrapper_handler calls, and
wrapper_handler is getting the blame. I don't see how pqsignal_handlers
could be uninitialized. It's static, and we are careful to set it
appropriately before we call sigaction().
--
nathan
