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bug#47067: 28.0.50; [feature/native-comp] Crash while scrolling through
From: |
Pip Cet |
Subject: |
bug#47067: 28.0.50; [feature/native-comp] Crash while scrolling through dispnew.c |
Date: |
Sat, 13 Mar 2021 16:32:50 +0000 |
On Sat, Mar 13, 2021 at 4:21 PM Eli Zaretskii <eliz@gnu.org> wrote:
> > From: Pip Cet <pipcet@gmail.com>
> > Date: Sat, 13 Mar 2021 15:45:52 +0000
> > Cc: Andrea Corallo <akrl@sdf.org>, 47067@debbugs.gnu.org
> >
> > On Sat, Mar 13, 2021 at 3:27 PM Eli Zaretskii <eliz@gnu.org> wrote:
> > > > > It's nowhere in the C backtrace, only its caller
> > > >
> > > > But it was in one of the previous backtraces?
> > >
> > > Too many moons ago. The ABI was bumped since then, and so did the
> > > *.eln files.
> >
> > The code you pasted matches c-beginning-of-statement-1, and so does
> > the Lisp backtrace, so I would suggest we go with it...
>
> I don't know how to go with it: the backtrace is truncated (for
> reasons I don't yet understand) before it gets to it.
I'm pretty sure the first ?? is c-beginning-of-stmt-1. It's a function
with five arguments, at least.
> > > > So EDI is bunk at this point. Can you go back a bit further to where
> > > > it's initialized?
> > >
> > > Sorry, I don't understand: I gave you the disassembly of 512 bytes
> > > before, isn't that enough to see where EDI is assigned the value? Or
> > > what do you mean by "go back"?
> >
> > It's not enough, no. we're looking for an insn of the form mov XXX,
> > %edi or lea XXX, %edi, or anything like that.
>
> I went back 4KB, and the only two instructions that write into EDI are
It's a long function, that might not have been enough.
> the following:
>
> 0x09e3159d: mov -0x100(%ebp),%edi
> 0x09e31c71: mov 0x9f37b9c,%edi
>
> > I'm suspicious because EDI is a register variable that is clobbered
> > somehow right after a setjmp returned. Which setjmp implementation are
> > you using?
>
> Not sure how to answer that. AFAIK, it's a setjmp from the MS runtime.
So not some mingw wrapper for it? I just checked the only "mingw"-like
sources I could find, and they don't appear to use the frame pointer
argument properly...
> > Is it possible that you're on Windows, but unlike other Windows
> > setjmps, it's unsafe to call your setjmp through a function pointer?
>
> How do I tell?
Well, you could just apply this untested patch, fix any obvious
compile errors I might not have spotted, and try to reproduce it. I'm
not currently on a Windows (or x86) machine, so it's a bit hard for me
to test...
> And why I never had any problems with setjmp elsewhere in Emacs,
> although we use it all the time in keyboard.c and elsewhere?
It's only natively-compiled code that attempts to call setjmp through
a function pointer. This was fixed in the POSIX case, but I didn't
touch the Windows code because I assumed that they used the extra
argument in their non-standard API to do this right...
> Here's an interesting factoid: while most addresses in the backtraces
> I see with this recipe are identical from run to run, the 'fun'
> arguments of funcall_lambda's aren't. Compare the backtrace I sent 3
> messages ago with this one:
>
> #0 0x01236964 in arithcompare_driver (nargs=2, args=0x28,
> comparison=ARITH_LESS) at data.c:2673
> #1 0x01236a3c in Flss (nargs=2, args=0x28) at data.c:2691
> #2 0x09e32285 in ?? ()
> #3 0x01261a74 in funcall_lambda (fun=XIL(0xa000000007650188), nargs=5,
> arg_vector=0x826a08) at eval.c:3292
> #4 0x012603c9 in Ffuncall (nargs=6, args=0x826a00) at eval.c:3013
> #5 0x09ea0dbf in ?? ()
> #6 0x012603c9 in Ffuncall (nargs=1, args=0x826bd8) at eval.c:3013
> #7 0x09e8e041 in ?? ()
> #8 0x01261a74 in funcall_lambda (fun=XIL(0xa00000000778d5b8), nargs=1,
> arg_vector=0x826db8) at eval.c:3292
> #9 0x012603c9 in Ffuncall (nargs=2, args=0x826db0) at eval.c:3013
> #10 0x70895b36 in
> F632d666f6e742d6c6f636b2d6375742d6f66662d6465636c617261746f7273_c_font_lock_cut_off_declarators_0
> ()
> from
> d:\usr\eli\.emacs.d\eln-cache\28.0.50-7d88f6c1\cc-fonts-d7d8a7f5-b7c359cd.eln
> #11 0x01261a74 in funcall_lambda (fun=XIL(0xa000000007785f78), nargs=1,
> arg_vector=0x827050) at eval.c:3292
> #12 0x012603c9 in Ffuncall (nargs=2, args=0x827048) at eval.c:3013
> #13 0x068daf93 in ?? ()
> #14 0x012dea14 in helper_save_restriction () at comp.c:4575
> #15 0x0122eb86 in wrong_type_argument (predicate=XIL(0x892404890c245c89),
> value=XIL(0x8244c89e45d8be0)) at data.c:143
> Backtrace stopped: previous frame inner to this frame (corrupt stack?)
>
> Note how arguments to Funcall's are the same, whereas arguments to
> funcall_lambda's aren't. Even the garbage in the 2 arguments to
> wrong_type_argument are identical.
Which non-stack addresses are invariant in that backtrace?
> Sounds like something is uninitialized somewhere? Hmm...
Maybe...
Pip
bug46824.diff
Description: Text Data
- bug#47067: 28.0.50; [feature/native-comp] Crash while scrolling through dispnew.c, (continued)
- bug#47067: 28.0.50; [feature/native-comp] Crash while scrolling through dispnew.c, Eli Zaretskii, 2021/03/12
- bug#47067: 28.0.50; [feature/native-comp] Crash while scrolling through dispnew.c, Pip Cet, 2021/03/13
- bug#47067: 28.0.50; [feature/native-comp] Crash while scrolling through dispnew.c, Eli Zaretskii, 2021/03/13
- bug#47067: 28.0.50; [feature/native-comp] Crash while scrolling through dispnew.c, Pip Cet, 2021/03/13
- bug#47067: 28.0.50; [feature/native-comp] Crash while scrolling through dispnew.c, Eli Zaretskii, 2021/03/13
- bug#47067: 28.0.50; [feature/native-comp] Crash while scrolling through dispnew.c, Eli Zaretskii, 2021/03/13
- bug#47067: 28.0.50; [feature/native-comp] Crash while scrolling through dispnew.c, Pip Cet, 2021/03/13
- bug#47067: 28.0.50; [feature/native-comp] Crash while scrolling through dispnew.c, Eli Zaretskii, 2021/03/13
- bug#47067: 28.0.50; [feature/native-comp] Crash while scrolling through dispnew.c, Pip Cet, 2021/03/13
- bug#47067: 28.0.50; [feature/native-comp] Crash while scrolling through dispnew.c, Eli Zaretskii, 2021/03/13
- bug#47067: 28.0.50; [feature/native-comp] Crash while scrolling through dispnew.c,
Pip Cet <=
- bug#47067: 28.0.50; [feature/native-comp] Crash while scrolling through dispnew.c, Eli Zaretskii, 2021/03/13
- bug#47067: 28.0.50; [feature/native-comp] Crash while scrolling through dispnew.c, Pip Cet, 2021/03/13
- bug#47067: 28.0.50; [feature/native-comp] Crash while scrolling through dispnew.c, Eli Zaretskii, 2021/03/13
- bug#47067: 28.0.50; [feature/native-comp] Crash while scrolling through dispnew.c, Pip Cet, 2021/03/13
- bug#47067: 28.0.50; [feature/native-comp] Crash while scrolling through dispnew.c, Eli Zaretskii, 2021/03/13
- bug#47067: 28.0.50; [feature/native-comp] Crash while scrolling through dispnew.c, Andrea Corallo, 2021/03/13
- bug#47067: 28.0.50; [feature/native-comp] Crash while scrolling through dispnew.c, Pip Cet, 2021/03/13
- bug#47067: 28.0.50; [feature/native-comp] Crash while scrolling through dispnew.c, Andrea Corallo, 2021/03/13
- bug#47067: 28.0.50; [feature/native-comp] Crash while scrolling through dispnew.c, Andrea Corallo, 2021/03/13
- bug#47067: 28.0.50; [feature/native-comp] Crash while scrolling through dispnew.c, Eli Zaretskii, 2021/03/14