linux-kernel - Re: [PATCH] mm: folio-compat: fix bug for pagecache_get

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Message-ID: <Y066q/QNrBSRjPux@casper.infradead.org>
Date:   Tue, 18 Oct 2022 15:39:39 +0100
From:   Matthew Wilcox <willy@...radead.org>
To:     Tuo Cao <91tuocao@...il.com>
Cc:     akpm@...ux-foundation.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm: folio-compat: fix bug for pagecache_get_page

On Tue, Oct 18, 2022 at 10:36:39PM +0800, Tuo Cao wrote:
> The folio returned from __filemap_get_folio may be a NULL, it will
> causes the kernel crash when access folio->page.

This is not a bug.  &folio->page does not dereference folio but performs
pointer arithmetic.