From: Andrea Corallo <akrl@sdf.org>
To: Eli Zaretskii <eliz@gnu.org>
Cc: silent2600@gmail.com, emacs-devel@gnu.org
Subject: Re: changed dlopen flags in dynlib.c, gccemacs crash
Date: Thu, 09 Dec 2021 20:47:57 +0000 [thread overview]
Message-ID: <xjfh7bhtshu.fsf@ma.sdf.org> (raw)
In-Reply-To: <834k7iugit.fsf@gnu.org> (Eli Zaretskii's message of "Thu, 09 Dec 2021 14:08:58 +0200")
Eli Zaretskii <eliz@gnu.org> writes:
>> From: Andrea Corallo <akrl@sdf.org>
>> Cc: hx <silent2600@gmail.com>, emacs-devel@gnu.org
>> Date: Thu, 09 Dec 2021 10:53:57 +0000
>>
>> > Andrea, any better ideas? I don't understand the reason for the
>> > crash, as we seem to have defenses against this in Fnative_elisp_load,
>> > so I'm probably missing something.
>>
>> Hello all,
>>
>> I'm no expert on 'dlopen' so I'm not sure about the impact of using
>> RTLD_GLOBAL. But should be noted that .eln files do share a number of
>> symbol names, I'm wondering if this could be somehow problematic when
>> using RTLD_GLOBAL, that's my suspect here.
>
> Assuming the RTLD_GLOBAL flag was added.
Yep
> But still, the crash is because we assume a Lisp object is a cons cell
> and take its CDR. So evidently it isn't a cons cell (probably nil),
> and I don't understand how that could be caused, not even if
> RTLD_GLOBAL was used.
I'm just speculating *but*: `comp--register-lambda' it's called directly
from the eln synthetized code that is run when the .eln is loaded.
The arguments of `comp--register-lambda' are immediates that are set
into the eln not long before, and this process (in 'load_comp_unit')
indeed requires symbol resolution (through our `dynlib_sym').
My guess is that something goes wrong in that area (but as mentioned
I've no proof of that).
Andrea
next prev parent reply other threads:[~2021-12-09 20:47 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-08 6:01 changed dlopen flags in dynlib.c, gccemacs crash hx
2021-12-08 13:15 ` Eli Zaretskii
2021-12-09 0:51 ` hx
2021-12-09 8:37 ` Eli Zaretskii
2021-12-09 10:53 ` Andrea Corallo
2021-12-09 12:08 ` Eli Zaretskii
2021-12-09 20:47 ` Andrea Corallo [this message]
2021-12-11 2:29 ` hx
2021-12-11 8:23 ` Eli Zaretskii
2021-12-11 18:09 ` Andrea Corallo
2021-12-11 18:23 ` Eli Zaretskii
2021-12-11 20:53 ` Andrea Corallo
2021-12-15 15:26 ` Andrea Corallo
2021-12-15 16:59 ` Eli Zaretskii
2022-03-06 14:32 ` Philipp Stephani
2022-03-06 15:32 ` Eli Zaretskii
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