linux-kernel - Re: module: preserve Elf information for livepatch modules

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Date:	Wed, 16 Dec 2015 19:40:50 -0500
From:	Jessica Yu <jeyu@...hat.com>
To:	Miroslav Benes <mbenes@...e.cz>
Cc:	Rusty Russell <rusty@...tcorp.com.au>,
	Josh Poimboeuf <jpoimboe@...hat.com>,
	Seth Jennings <sjenning@...hat.com>,
	Jiri Kosina <jikos@...nel.org>,
	Vojtech Pavlik <vojtech@...e.com>,
	Jonathan Corbet <corbet@....net>, linux-api@...r.kernel.org,
	live-patching@...r.kernel.org, x86@...nel.org,
	linux-kernel@...r.kernel.org, linux-s390@...r.kernel.org,
	linux-doc@...r.kernel.org
Subject: Re: module: preserve Elf information for livepatch modules

+++ Miroslav Benes [16/12/15 11:58 +0100]:
>On Mon, 30 Nov 2015, Jessica Yu wrote:
>
>> @@ -3530,6 +3614,16 @@ static int load_module(struct load_info *info, const char __user *uargs,
>>  	if (err < 0)
>>  		goto bug_cleanup;
>>
>> +	/*
>> +	 * Save sechdrs, indices, and other data from info
>> +	 * in order to patch to-be-loaded modules.
>> +	 * Do not call free_copy() for livepatch modules.
>> +	 */
>> +	if (mod->klp)
>> +		err = copy_module_elf(mod, info);
>> +	if (err < 0)
>> +		goto bug_cleanup;
>> +
>
>I think goto bug_cleanup is not sufficient. Just before this hunk sysfs is
>created. So in case of error here we should call mod_sysfs_teardown() or
>something before going to bug_cleanup. That is new error label is needed
>before bug_cleanup. Correct?

Yes I think you're right. So before bug_cleanup, we'll just need a new
label (maybe called sysfs_cleanup) that calls mod_sysfs_teardown(). In
addition, the if (err < 0) check should have been enclosed in the if
(mod->klp) block.

Jessica
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