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Message-Id: <060F1E17-ECD0-41F5-B635-2A0E16967433@gmx.com>
Date: Thu, 19 Apr 2018 09:18:53 +0800
From: "cgxu519@....com" <cgxu519@....com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: "cgxu519@....com" <cgxu519@....com>, linux-fsdevel@...r.kernel.org,
dhowells@...hat.com, kstewart@...uxfoundation.org,
gregkh@...uxfoundation.org, tglx@...utronix.de,
pombredanne@...b.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] hfs: fix potential refcnt problem of nls module
在 2018年4月19日,上午3:42,Andrew Morton <akpm@...ux-foundation.org> 写道:
>
> On Tue, 17 Apr 2018 15:05:32 +0800 Chengguang Xu <cgxu519@....com> wrote:
>
>> When specifying iocharset/codepage multiple times in a mount,
>> current option parsing will cause inaccurate refcount of nls
>> module. Hence, call unload_nls for previous one in this case.
>>
>> ...
>>
>> --- a/fs/hfs/super.c
>> +++ b/fs/hfs/super.c
>> @@ -329,8 +329,10 @@ static int parse_options(char *options, struct hfs_sb_info *hsb)
>> return 0;
>> }
>> p = match_strdup(&args[0]);
>> - if (p)
>> + if (p) {
>> + unload_nls(hsb->nls_disk);
>> hsb->nls_disk = load_nls(p);
>> + }
>> if (!hsb->nls_disk) {
>> pr_err("unable to load codepage \"%s\"\n", p);
>> kfree(p);
>> @@ -344,8 +346,10 @@ static int parse_options(char *options, struct hfs_sb_info *hsb)
>> return 0;
>> }
>> p = match_strdup(&args[0]);
>> - if (p)
>> + if (p) {
>> + unload_nls(hsb->nls_io);
>> hsb->nls_io = load_nls(p);
>> + }
>> if (!hsb->nls_io) {
>> pr_err("unable to load iocharset \"%s\"\n", p);
>> kfree(p);
>
> Confused.
>
> break;
> : case opt_codepage:
> : if (hsb->nls_disk) {
> : pr_err("unable to change codepage\n");
> : return 0;
> : }
>
> Here, hsb->nls_disk is known to be zero.
>
> : p = match_strdup(&args[0]);
> : if (p) {
> : unload_nls(hsb->nls_disk);
>
> So this will always do unload_nls(0).
>
> : hsb->nls_disk = load_nls(p);
> : }
>
> And the same applies to your opt_iocharset change.
You are right. Sorry I just misread this part, please just drop the patch.
Thanks.
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