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Message-ID: <ZmxIvIJ3YSZDwbPW@casper.infradead.org>
Date: Fri, 14 Jun 2024 14:42:20 +0100
From: Matthew Wilcox <willy@...radead.org>
To: Hillf Danton <hdanton@...a.com>
Cc: linux-mm@...ck.org, Hugh Dickins <hughd@...gle.com>,
Johannes Weiner <hannes@...xchg.org>, Jan Kara <jack@...e.cz>,
Andrew Morton <akpm@...ux-foundation.org>,
linux-kernel@...r.kernel.org,
syzbot+d79afb004be235636ee8@...kaller.appspotmail.com
Subject: Re: [RFC PATCH] mm: truncate: flush lru cache for evicted inode
On Fri, Jun 14, 2024 at 09:18:56PM +0800, Hillf Danton wrote:
> Flush lru cache to avoid folio->mapping uaf in case of inode teardown.
What? inodes are supposed to have all their folios removed before
being freed. Part of removing a folio sets the folio->mapping to NULL.
Where is the report?
> Reported-and-tested-by: syzbot+d79afb004be235636ee8@...kaller.appspotmail.com
> Signed-off-by: Hillf Danton <hdanton@...a.com>
> ---
> Post for comments because lru_add_drain_all() is too haevy a hammer.
>
> --- x/mm/truncate.c
> +++ y/mm/truncate.c
> @@ -419,6 +419,9 @@ void truncate_inode_pages_range(struct a
> truncate_folio_batch_exceptionals(mapping, &fbatch, indices);
> folio_batch_release(&fbatch);
> }
> +
> + if (mapping_exiting(mapping))
> + lru_add_drain_all();
> }
> EXPORT_SYMBOL(truncate_inode_pages_range);
>
> --
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