linux-kernel - Re: [PATCH 5.15 v3] mm/filemap: fix UAF in find_lock

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Date:   Thu, 7 Jul 2022 09:25:36 +0800
From:   Liu Shixin <liushixin2@...wei.com>
To:     Matthew Wilcox <willy@...radead.org>
CC:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Jan Kara <jack@...e.cz>,
        William Kucharski <william.kucharski@...cle.com>,
        Christoph Hellwig <hch@....de>, <linux-kernel@...r.kernel.org>,
        <stable@...r.kernel.org>
Subject: Re: [PATCH 5.15 v3] mm/filemap: fix UAF in find_lock_entries



On 2022/7/6 22:08, Matthew Wilcox wrote:
> On Wed, Jul 06, 2022 at 03:45:27PM +0800, Liu Shixin wrote:
>>  	rcu_read_lock();
>>  	while ((page = find_get_entry(&xas, end, XA_PRESENT))) {
>> +		unsigned long next_idx = xas.xa_index;
> It's confusing to have next_idx not be the actual next index.
> That was why I made it 'xas.xa_index + 1'.  I know it's somewhat
> used as an indicator that we don't need to call xas_set(), and so
> it doesn't really matter, but let's say what we mean.
I'll modify it and resend again, thanks.
>
>
> .
>