From: Peter Stephenson <p.w.stephenson@ntlworld.com>
To: "zsh-workers@zsh.org" <zsh-workers@zsh.org>
Subject: Re: [BUG] Two vulnerabilities in zsh
Date: Tue, 19 May 2020 21:38:55 +0100 [thread overview]
Message-ID: <c921824332bf2ca7bc6cff15bc7ffa0042b22677.camel@ntlworld.com> (raw)
In-Reply-To: <20200519170418.5bc00b2f@tarpaulin.shahaf.local2>
On Tue, 2020-05-19 at 17:04 +0000, Daniel Shahaf wrote:
> > 1. Execute the following PoC command:
> >
> > echo $'******** **********************$\\\n(>$' | zsh
>
> This instruction is underspecified because it does not identify «echo»
> implementation being used and the shell being used (which affects how
> the «$'…'» would be parsed). That aside, I can reproduce this:
>
> $ printf '******** **********************$\\\n(>$' | zsh -f
> BUG: parse error in command substitution
> Segmentation fault
> $
The BUG message simplifies to this:
(127)9:32% zsh -fc '$\
('
1: BUG: parse error in command substitution
zsh:1: no such file or directory: pws/.
The other output shows it's doing something it shouldn't even if there
isn't a crash as a result. Adding a command in front does produce a
crash.
I think the backslashed newline is valid, and it looks like it's usually
correctly handled; apparently its presence is disguising the bad input
in this case.
pws
next prev parent reply other threads:[~2020-05-19 20:39 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-19 6:48 Aaron Esau
2020-05-19 17:04 ` Daniel Shahaf
2020-05-19 20:38 ` Peter Stephenson [this message]
2020-05-20 0:45 ` Daniel Shahaf
2020-05-22 18:56 ` Peter Stephenson
2020-05-22 21:47 ` Peter Stephenson
2020-05-23 2:17 ` Daniel Shahaf
2020-05-23 16:45 ` Peter Stephenson
2020-05-20 0:40 ` [BUG] Two vulnerabilities in zsh - #1 :: null dereference in check_colon_subscript in subst.c Daniel Shahaf
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