linux-kernel - Re: [RFC 3/5] modules, x86: use vmalloc

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <2063847A-42D6-4A26-992F-0DD32A5E1F05@fb.com>
Date:   Fri, 7 Oct 2022 06:46:49 +0000
From:   Song Liu <songliubraving@...com>
To:     Luis Chamberlain <mcgrof@...nel.org>
CC:     Song Liu <song@...nel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "x86@...nel.org" <x86@...nel.org>,
        "peterz@...radead.org" <peterz@...radead.org>,
        "hch@....de" <hch@....de>, Kernel Team <Kernel-team@...com>,
        "rick.p.edgecombe@...el.com" <rick.p.edgecombe@...el.com>,
        "dave.hansen@...el.com" <dave.hansen@...el.com>
Subject: Re: [RFC 3/5] modules, x86: use vmalloc_exec for module core



> On Oct 6, 2022, at 4:38 PM, Luis Chamberlain <mcgrof@...nel.org> wrote:
> 
> On Thu, Aug 18, 2022 at 03:42:16PM -0700, Song Liu wrote:
>> diff --git a/arch/x86/kernel/module.c b/arch/x86/kernel/module.c
>> index 100446ffdc1d..570af623e28f 100644
>> --- a/arch/x86/kernel/module.c
>> +++ b/arch/x86/kernel/module.c
>> @@ -229,6 +229,7 @@ int apply_relocate_add(Elf64_Shdr *sechdrs,
>> 	bool early = me->state == MODULE_STATE_UNFORMED;
>> 	void *(*write)(void *, const void *, size_t) = memcpy;
>> 
>> +	early = false;
>> 	if (!early) {
>> 		write = text_poke;
>> 		mutex_lock(&text_mutex);
> 
> As per 88fc078a7a8f6 ("x86/module: Use text_poke() for late
> relocations") I'm curious why we have to take the live patching
> path now all the time?

Since vmalloc_exec returns read-only memory, we need text_poke()
for any operation to it. 

Does this answer your question?

Song