Re: [PATCH ima-evm-utils v3 07/11] Add tests for EVM portable signatures

From: Stefan Berger <stefanb@linux.ibm.com>
To: Roberto Sassu <roberto.sassu@huaweicloud.com>,
	zohar@linux.ibm.com, dmitry.kasatkin@gmail.com
Cc: linux-integrity@vger.kernel.org, vt@altlinux.org, pvorel@suse.cz,
	Roberto Sassu <roberto.sassu@huawei.com>
Subject: Re: [PATCH ima-evm-utils v3 07/11] Add tests for EVM portable signatures
Date: Wed, 25 Jan 2023 18:15:14 -0500	[thread overview]
Message-ID: <d9c60317-5371-6d3a-3f7c-c71011e0a126@linux.ibm.com> (raw)
In-Reply-To: <20230125085030.1568256-8-roberto.sassu@huaweicloud.com>

On 1/25/23 03:50, Roberto Sassu wrote:
> From: Roberto Sassu <roberto.sassu@huawei.com>
> 

> +
> +	last_char=${ima_xattr: -1}

To avoid last_char from spilling into the global variable space I would declare it as local. I would do this for **every** variable.

An example from functions.sh:

_evmctl_run() {
   local op=$1 out=$1-$$.out
   local text_for=${FOR:+for $ADD_TEXT_FOR}
   # Additional parameters:
   # ADD_DEL: additional files to rm on failure
   # ADD_TEXT_FOR: append to text as 'for $ADD_TEXT_FOR'

   cmd="evmctl $V $EVMCTL_ENGINE $*"
   echo $YELLOW$TMODE "$cmd"$NORM
   $cmd >"$out" 2>&1
   ret=$?

[...]
}

If I have a function like this here calling _evmctl_run() it will clobber even my local-declared ret and cmd variables because neither is declared as local in _evmctl_run.

foo() {
   local ret=123
   local cmd="mycmd"
   [...]
   _evmctl_run ...
   # my ret and cmd are now clobbered!
}

   Stefan