From: Tom de Vries <firstname.lastname@example.org>
To: Mark Wielaard <email@example.com>, firstname.lastname@example.org
Subject: Re: Fwd: Buildbot failure in Wildebeest Builder on whole buildset
Date: Thu, 25 Mar 2021 15:01:57 +0100 [thread overview]
Message-ID: <email@example.com> (raw)
On 3/25/21 11:49 AM, Mark Wielaard wrote:
> Hi Tom,
> On Thu, 2021-03-25 at 11:41 +0100, Mark Wielaard wrote:
>> On Thu, 2021-03-25 at 09:50 +0100, Tom de Vries wrote:
>>> I've just committed patch "Move hardlink handling out of dwz
>>> and there's this buildbot failure.
>>> Is there something easy that you can do to find out if this is a
>>> or not, f.i. retry the build for that bot?
>> I logged into the buildbot worker and did a dwz build myself.
>> make check does produce 32 unexpected failures.
>> Removing the last commit makes everything pass.
>> Adding the commit again produces the failures again.
>> It isn't a fluke.
>> The problem is simply that:
>> cp hello 1
>> dwz 1
>> Makes dwz produce an exit code of 1 which seems to be interpreted as
>> child process exited abnormally in a make check run.
>> running under valgrind --track-origins=yes gives:
>> ==31313== Conditional jump or move depends on uninitialised value(s)
>> ==31313== at 0x127974: dwz (dwz.c:15287)
>> ==31313== by 0x10BB7C: dwz_with_low_mem (dwz.c:16227)
>> ==31313== by 0x10BB7C: dwz_one_file (dwz.c:16253)
>> ==31313== by 0x10BB7C: main (dwz.c:16532)
>> ==31313== Uninitialised value was created by a stack allocation
>> ==31313== at 0x10B59B: main (dwz.c:16513)
>> I haven't tracked down what res->res precisely depends on that
>> have a defined value.
> Note that dwz_one_file was inlined into main, causing valgrind to
> pinpoint the wrong frame. Without inlining we get:
> ==2502== Conditional jump or move depends on uninitialised value(s)
> ==2502== at 0x13CF4F: dwz (dwz.c:15287)
> ==2502== by 0x13FE3A: dwz_with_low_mem (dwz.c:16227)
> ==2502== by 0x13FEAE: dwz_one_file (dwz.c:16253)
> ==2502== by 0x140B59: main (dwz.c:16532)
> ==2502== Uninitialised value was created by a stack allocation
> ==2502== at 0x13FE7F: dwz_one_file (dwz.c:16245)
> And indeed we see:
> static int
> dwz_one_file (const char *file, const char *outfile)
> struct file_result res;
> if (stats_p)
> init_stats (file);
> res.die_count = 0;
> return dwz_with_low_mem (file, outfile, &res, NULL);
> Defines and passes down res, but only initializes the die_count field.
> Then in dwz_with_low_mem we simply pass that res to dwz:
> ret = (low_mem_die_limit == 0
> ? 2
> : dwz (file, outfile, res));
> And in dwz the first thing we do is:
> if (res->res == -1)
> return 1;
> But res->res was never given a value and so could be anything.
thanks for helping out with this.
I've fixed this now, and verified that the buildbot is back to all-green.
After seeing your analysis, I realized I had tried -fsanitize=address
but not valgrind, and indeed using valgrind I managed to reproduce the
I've submitted a patch proposing a check-valgrind target in the
Makefile, to remind me to try this next time.
prev parent reply other threads:[~2021-03-25 14:01 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-25 8:41 buildbot
2021-03-25 8:50 ` Fwd: " Tom de Vries
2021-03-25 10:41 ` Mark Wielaard
2021-03-25 10:49 ` Mark Wielaard
2021-03-25 14:01 ` Tom de Vries [this message]
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