Date: Sun, 6 Mar 2022 04:26:10 +0700 From: Eugene Grosbein <eugen@grosbein.net> To: Peter <pmc@citylink.dinoex.sub.org>, freebsd-stable@freebsd.org, Konstantin Belousov <kib@freebsd.org> Subject: Re: Program crashes on stable/13 (but not on 12.3) Message-ID: <bf0ed399-f0e6-c98e-4d6f-d2da10af261f@grosbein.net> In-Reply-To: <YiO5cO967R/D2cIm@gate.intra.daemon.contact> References: <YiO5cO967R/D2cIm@gate.intra.daemon.contact>
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06.03.2022 2:26, Peter wrote:
Adding kib@ to CC: in case this is connected to recent commit by him.
> Hija,
>
> this program crashes SEGV on stable/13 after 135962 iterations,
> but continues to run on 12.3.
>
> My stable/13 is still at 22ba2970766 - if You happen to be on a
> newer level, then please just try this out.
>
> ------------------------------------------------------
> #include <unistd.h>
> #include <fcntl.h>
> #include <stdio.h>
>
> main() {
> char buf[] = "12345678901234567890123456789012345678901234567890";
> int fd = open("/dev/null", O_RDONLY);
> int i = 0;
>
> close(1);
> dup2(fd, 1);
> close(fd);
>
> while(1) {
> fputs(buf, stdout);
> fflush(stdout);
> i++;
> fprintf(stderr, "%d\n", i);
> }
> }
> ------------------------------------------------------
>
> I know that the code is bogus, but this is exactly what one of our
> ports does (and why it started to crash after upgrading to stable/13).
>
> And I think it should not SEGV, anyway.
>
> For the full story, read here:
>
> https://forums.freebsd.org/threads/random-program-crashes-no-coredumps-and-error-94.84285/
fflush() in our libc recently got some change due to very old PR
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=76398
That change was merged to stable/13 after 13.0-RELEASE:
https://cgit.freebsd.org/src/commit/?id=afa9a1f5ec9974793a8744c55036ef5c4d08903d
I wonder if it could be connected to the problem in question,
so adding kib@ to CC: (I am sorry, Konstantin).
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