linux-kernel - Re: execve for script don't return ENOEXEC, bug ?

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Message-Id: <20100319140704.794dec89.akpm@linux-foundation.org>
Date:	Fri, 19 Mar 2010 14:07:04 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Valery Reznic <valery_reznic@...oo.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: execve for script don't return ENOEXEC, bug ?

On Thu, 11 Mar 2010 02:56:16 -0800 (PST)
Valery Reznic <valery_reznic@...oo.com> wrote:

> Hi,
> 
> I Have following to scripts:
> 
> a.sh
> #!/bin/sh
> echo "It's a.sh
> 
> and b.sh:
> #! ./b.sh
> echo "It's b.sh"
> 
> As per execve man page, script interpreter should not be script itself.
> When I run it on my Fedora 8 x86_64 box (with stock kernel, never updated)
> under strace I got following:
> 
> strace -f -e execve  setarch x86_64  ./b.sh 
> execve("/usr/bin/setarch", ["setarch", "x86_64", "./b.sh"], [/* 23 vars */]) = 0
> execve("./b.sh", ["./b.sh"], [/* 23 vars */]) = -1 ENOEXEC (Exec format error)
> execve("/bin/sh", ["/bin/sh", "./b.sh"], [/* 23 vars */]) = 0
> It's b.sh
> 
> I.e execve failed as it should
> 
> When I run same scripts on Fedora 12 x86_64 box with stock kernel 2.6.31.5-127.fc12.x86_64 I got following:
> 
> strace -f -e execve setarch i386  ./b.sh 
> execve("/usr/bin/setarch", ["setarch", "i386", "./b.sh"], [/* 41 vars */]) = 0
> execve("./b.sh", ["./b.sh"], [/* 41 vars */]) = 0
> It's a.sh
> 
> I.e execve succeeded, instead of failing with ENOEXEC
> 

It works for me, I think:

z:/home/akpm> uname -a
Linux z 2.6.31.5-127.fc12.x86_64 #1 SMP Sat Nov 7 21:11:14 EST 2009 x86_64 x86_64 x86_64 GNU/Linux
z:/home/akpm> cat b.sh
#! ./b.sh
echo "It's b.sh"
z:/home/akpm> strace -f -e execve setarch i386  ./b.sh 
execve("/usr/bin/setarch", ["setarch", "i386", "./b.sh"], [/* 60 vars */]) = 0
execve("./b.sh", ["./b.sh"], [/* 60 vars */]) = -1 ENOEXEC (Exec format error)
execve("/bin/sh", ["/bin/sh", "./b.sh"], [/* 60 vars */]) = 0
It's b.sh


Did I do something wrong?  If not, I wonder what's different.
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