From: Jan Chaloupka <jchaloup@redhat.com>
To: 18140@debbugs.gnu.org
Subject: bug#18140: [PATCH] macros.c: CHECK_VECTOR_OR_STRING invokes wrong_type_argument for Qnil instead of return 0
Date: Tue, 29 Jul 2014 10:23:52 +0200 [thread overview]
Message-ID: <53D75A18.8000508@redhat.com> (raw)
In-Reply-To: <mvmk36wha9p.fsf@hawking.suse.de>
On 07/29/2014 09:52 AM, Andreas Schwab wrote:
> Jan Chaloupka <jchaloup@redhat.com> writes:
>
>> Changelog:
>> line wrapping to 80 characters
>>
>> In function Fstart_kbd_macro (macros.c), Vlast_kbd_macro of current_kboard is
>> Qnil for the first invocation. If NILP (append) is false,
>> current_kboard->kbd_macro_ptr has random value (in our case
>> 0x5353535353535353), which after CHECK_VECTOR_OR_STRING failure (invocation
>> of wrong_type_argument) results in garbage collecting.
>> During gc, marking of objects is processed and mark_kboards (keyboard.c) is
>> invoked. Following for loop is fired:
>>
>> for (p = kb->kbd_macro_buffer; p < kb->kbd_macro_ptr; p++)
>> mark_object (*p);
>>
>> Since kb->kbd_macro_ptr is set to 0x5353535353535353, mark_object (*p) is
>> trying to mark object on address out of memory space (or memory that
>> cannot be accessed). Thus resulting in SIGSEGV signal.
> So the correct solution is to initialize kbd_macro_ptr together with
> kbd_macro_buffer. Otherwise the same situation can still happen any
> time garbage collection is called.
Yes, for garbage collector. However, Vlast_kbd_macro will continue being
Qnil.
The patch is still valid (just without comment about random value of
kbd_macro_ptr and garbage collection):
In function Fstart_kbd_macro (macros.c), Vlast_kbd_macro of
current_kboard is
Qnil for the first invocation. If NILP (append) is false
CHECK_VECTOR_OR_STRING fails (invocation
of wrong_type_argument resulting in emacs_abort). However, it has to pass.
> Andreas.
>
next prev parent reply other threads:[~2014-07-29 8:23 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20140729053056.14713.45327.stgit@unused-4-157.brq.redhat.com>
2014-07-29 5:35 ` bug#18140: [PATCH] macros.c: CHECK_VECTOR_OR_STRING invokes wrong_type_argument for Qnil instead of return 0 Jan Chaloupka
2014-07-29 7:52 ` Andreas Schwab
2014-07-29 8:23 ` Jan Chaloupka [this message]
2014-07-29 8:37 ` Andreas Schwab
2014-07-29 8:55 ` Jan Chaloupka
2014-07-29 9:04 ` Andreas Schwab
2014-07-29 9:59 ` Jan Chaloupka
2014-07-29 10:05 ` Andreas Schwab
2014-07-29 8:10 ` Andreas Schwab
[not found] <20140728103721.7115.54163.stgit@unused-4-157.brq.redhat.com>
2014-07-29 5:01 ` Jan Chaloupka
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