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From: "Jun. T" <takimoto-j@kba.biglobe.ne.jp>
To: zsh-workers@zsh.org
Subject: Re: Probabilistic crash on zsh 5.9 on x86_64
Date: Wed, 12 Apr 2023 01:14:15 +0900	[thread overview]
Message-ID: <48A7DCE2-AEC1-4777-949C-50917EDCECB1@kba.biglobe.ne.jp> (raw)
In-Reply-To: <CAHYJk3QaY_ejw2gCw5d1BzyvB4W3EyU7cb1TWtZpRhx=QSpw+w@mail.gmail.com>

> 2023/04/09 6:36, Mikael Magnusson <mikachu@gmail.com> wrlte:

> It seems to happen reliably for me every time, with these messages,
> % MALLOC_CHECK_=3 zsh -fc 'TRAPEXIT() { ls }; TRAPEXIT'
> 1: parse.c:2817: Heap EPROG has nref > 0
> free(): invalid pointer
> zsh: abort      MALLOC_CHECK_=3 zsh -fc 'TRAPEXIT() { ls }; TRAPEXIT'

It seems memory pointed to by 'Eprog p' (in function freeeprog(),
parse.c:2817) is already freed.

If TRAPEXIT() is called directly, execshfunc(shf, ..) is called
with shf pointing to the node "TRAPEXIT" in shfunctab.
Then it calls

doshfunc(shf, ..)
  starttrapscope()			// exec.c:5821
    unsettrap()				// signals.c:1079
      shfunctab->freenode(shf)		// signals.c:982

this means shf is freed by freeshfuncnode(shf). But doshfunc()
continues to use shf (=shfunc in this function), and calls
  runshfunc(prog=shf->funcdef, ..)	// exec.c:5963
This leads to crash, of course.

The simplest thing we can do would be just to prohibit
users/scripts from calling TRAPEXIT() directly. I guess this
can be done by, for example, rejecting (with error message)
shf->node.nam=="TRAPEXIT" at the top of execshfunc(shf,..).

But then users can't test TRAPEXIT manually.

  reply	other threads:[~2023-04-11 16:15 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-04-08 17:28 zsh bug report throwaway email thing
2023-04-08 21:36 ` Mikael Magnusson
2023-04-11 16:14   ` Jun. T [this message]
2023-04-11 16:29     ` Peter Stephenson
2023-04-13 10:47       ` Peter Stephenson
2023-04-13 11:12         ` Peter Stephenson
2023-04-13 13:02           ` Jun. T
2023-04-13 13:19             ` Peter Stephenson
2023-04-13 14:03               ` Peter Stephenson
2023-04-13 14:13                 ` Peter Stephenson
2023-04-13 16:40                 ` Jun. T
2023-04-13 16:55                   ` Peter Stephenson
2023-04-14  8:29                     ` Peter Stephenson
2023-04-14 12:21                       ` Mikael Magnusson

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