GNU bug report logs - #50319
27.2; crash

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Devon Sean McCullough <Emacs-Hacker2020 <at> jovi.net>
To: bug-gnu-emacs <at> gnu.org
Subject: 27.2; crash
Date: Wed, 1 Sep 2021 09:30:57 -0400

Launch Emacs, attach a debugger, use it routinely for many weeks,
switching between various apps, until it dereferences a bad pointer
upon switching from some other app:

(lldb) process attach --pid 24105
⋮
Executable module set to "/Applications/Emacs.app/Contents/MacOS/Emacs-x86_64-10_14".
Architecture set to: x86_64h-apple-macosx-.
⋮
(lldb) Process 24105 stopped
* thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x172505fec)
    frame #0: 0x000000010cdcb104 Emacs-x86_64-10_14`redisplay_window + 4244
Emacs-x86_64-10_14`redisplay_window:
->  0x10cdcb104 <+4244>: movq   -0x14(%rbx), %rcx
    0x10cdcb108 <+4248>: addq   $-0x100, %rbx
    0x10cdcb10f <+4255>: testl  $0x100000, %ecx           ; imm = 0x100000
    0x10cdcb115 <+4261>: je     0x10cdcb0a0               ; <+4144>
Target 0: (Emacs-x86_64-10_14) stopped.
(lldb) bt all
* thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x172505fec)
  * frame #0: 0x000000010cdcb104 Emacs-x86_64-10_14`redisplay_window + 4244
    frame #1: 0x000000010cdc9799 Emacs-x86_64-10_14`redisplay_window_1 + 41
    frame #2: 0x000000010cec00af Emacs-x86_64-10_14`internal_condition_case_1 + 271
    frame #3: 0x000000010cd9f669 Emacs-x86_64-10_14`redisplay_internal + 4073
    frame #4: 0x000000010ce3d1a5 Emacs-x86_64-10_14`read_char + 2213
    frame #5: 0x000000010ce3ad6a Emacs-x86_64-10_14`read_key_sequence + 1722
    frame #6: 0x000000010ce3956c Emacs-x86_64-10_14`command_loop_1 + 1340
    frame #7: 0x000000010cebff77 Emacs-x86_64-10_14`internal_condition_case + 263
    frame #8: 0x000000010ce496f0 Emacs-x86_64-10_14`command_loop_2 + 48
    frame #9: 0x000000010cebf79b Emacs-x86_64-10_14`internal_catch + 267
    frame #10: 0x000000010cf7daa5 Emacs-x86_64-10_14`command_loop.cold.1 + 69
    frame #11: 0x000000010ce38633 Emacs-x86_64-10_14`command_loop + 131
    frame #12: 0x000000010ce38563 Emacs-x86_64-10_14`recursive_edit_1 + 115
    frame #13: 0x000000010ce387bb Emacs-x86_64-10_14`Frecursive_edit + 347
    frame #14: 0x000000010ce3734c Emacs-x86_64-10_14`main + 7436
    frame #15: 0x00007fff727ad3d5 libdyld.dylib`start + 1
    frame #16: 0x00007fff727ad3d5 libdyld.dylib`start + 1
  thread #2
    frame #0: 0x00007fff728e9616 libsystem_kernel.dylib`__select + 10
    frame #1: 0x000000010cf46e6c Emacs-x86_64-10_14`-[EmacsApp fd_handler:] + 236
    frame #2: 0x00007fff48a789a2 Foundation`__NSThread__start__ + 1194
    frame #3: 0x00007fff729a12eb libsystem_pthread.dylib`_pthread_body + 126
    frame #4: 0x00007fff729a4249 libsystem_pthread.dylib`_pthread_start + 66
    frame #5: 0x00007fff729a040d libsystem_pthread.dylib`thread_start + 13
  thread #3, name = 'com.apple.NSEventThread'
    frame #0: 0x00007fff728e221a libsystem_kernel.dylib`mach_msg_trap + 10
    frame #1: 0x00007fff728e2768 libsystem_kernel.dylib`mach_msg + 60
    frame #2: 0x00007fff46819e0e CoreFoundation`__CFRunLoopServiceMachPort + 328
    frame #3: 0x00007fff4681937c CoreFoundation`__CFRunLoopRun + 1612
    frame #4: 0x00007fff46818ade CoreFoundation`CFRunLoopRunSpecific + 455
    frame #5: 0x00007fff43e16bae AppKit`_NSEventThread + 175
    frame #6: 0x00007fff729a12eb libsystem_pthread.dylib`_pthread_body + 126
    frame #7: 0x00007fff729a4249 libsystem_pthread.dylib`_pthread_start + 66
    frame #8: 0x00007fff729a040d libsystem_pthread.dylib`thread_start + 13
  thread #23550
    frame #0: 0x00007fff728e3bfa libsystem_kernel.dylib`__workq_kernreturn + 10
    frame #1: 0x00007fff729a06e6 libsystem_pthread.dylib`_pthread_wqthread + 634
    frame #2: 0x00007fff729a03fd libsystem_pthread.dylib`start_wqthread + 13
  thread #23551
    frame #0: 0x00007fff728e3bfa libsystem_kernel.dylib`__workq_kernreturn + 10
    frame #1: 0x00007fff729a06e6 libsystem_pthread.dylib`_pthread_wqthread + 634
    frame #2: 0x00007fff729a03fd libsystem_pthread.dylib`start_wqthread + 13
  thread #23552
    frame #0: 0x00007fff728e3bfa libsystem_kernel.dylib`__workq_kernreturn + 10
    frame #1: 0x654d43505853536b
    frame #2: 0x00007fff729a03fd libsystem_pthread.dylib`start_wqthread + 13
  thread #23553
    frame #0: 0x0000000000000000
(lldb)

In GNU Emacs 27.2 (build 1, x86_64-apple-darwin18.7.0, NS appkit-1671.60 Version 10.14.6 (Build 18G95))
 of 2021-03-27 built on builder10-14.porkrind.org
Windowing system distributor 'Apple', version 10.3.1671
System Description:  Mac OS X 10.14.6

Configured using:
 'configure --with-ns '--enable-locallisppath=/Library/Application
 Support/Emacs/${version}/site-lisp:/Library/Application
 Support/Emacs/site-lisp' --with-modules'

Message #8 received at 50319 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Devon Sean McCullough <Emacs-Hacker2020 <at> jovi.net>
Cc: 50319 <at> debbugs.gnu.org
Subject: Re: bug#50319: 27.2; crash
Date: Wed, 01 Sep 2021 17:04:25 +0300

> From: Devon Sean McCullough <Emacs-Hacker2020 <at> jovi.net>
> Date: Wed, 1 Sep 2021 09:30:57 -0400
> 
> Launch Emacs, attach a debugger, use it routinely for many weeks,
> switching between various apps, until it dereferences a bad pointer
> upon switching from some other app:
> 
> (lldb) process attach --pid 24105
> ⋮
> Executable module set to "/Applications/Emacs.app/Contents/MacOS/Emacs-x86_64-10_14".
> Architecture set to: x86_64h-apple-macosx-.
> ⋮
> (lldb) Process 24105 stopped
> * thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x172505fec)
>      frame #0: 0x000000010cdcb104 Emacs-x86_64-10_14`redisplay_window + 4244
> Emacs-x86_64-10_14`redisplay_window:
> ->  0x10cdcb104 <+4244>: movq   -0x14(%rbx), %rcx
>      0x10cdcb108 <+4248>: addq   $-0x100, %rbx
>      0x10cdcb10f <+4255>: testl  $0x100000, %ecx           ; imm = 0x100000
>      0x10cdcb115 <+4261>: je     0x10cdcb0a0               ; <+4144>
> Target 0: (Emacs-x86_64-10_14) stopped.
> (lldb) bt all
> * thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x172505fec)
>    * frame #0: 0x000000010cdcb104 Emacs-x86_64-10_14`redisplay_window + 4244

Can you show where is this place in xdisp.c?  I'm afraid I cannot
figure that out from the disassembly alone.

Also, what did you do when it segfaulted? just clicked on an Emacs
frame with a mouse?  The backtrace doesn't look like a frame redraw,
it looks like a routine redisplay when Emacs becomes idle.

Thanks.

Message #13 received at 50319 <at> debbugs.gnu.org (full text, mbox):

From: Lars Ingebrigtsen <larsi <at> gnus.org>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: Devon Sean McCullough <Emacs-Hacker2020 <at> jovi.net>, 50319 <at> debbugs.gnu.org
Subject: Re: bug#50319: 27.2; crash
Date: Sun, 03 Oct 2021 11:40:41 +0200

Eli Zaretskii <eliz <at> gnu.org> writes:

> Can you show where is this place in xdisp.c?  I'm afraid I cannot
> figure that out from the disassembly alone.
>
> Also, what did you do when it segfaulted? just clicked on an Emacs
> frame with a mouse?  The backtrace doesn't look like a frame redraw,
> it looks like a routine redisplay when Emacs becomes idle.

This was a month ago, but there wasn't any further response to this, so
I think it sounds unlikely that we'll be making any further progress
here, and I'm closing this bug report.  If progress can be made, please
respond to the debbugs address and we'll reopen.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

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