From: Andrew Morton <akpm@linux-foundation.org>
To: Matthew Wilcox <willy@infradead.org>
Cc: Wan Jiabing <wanjiabing@vivo.com>,
Vlastimil Babka <vbabka@suse.cz>,
David Howells <dhowells@redhat.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Julia Lawall <Julia.Lawall@inria.fr>
Subject: Re: [PATCH] mm/filemap: Fix NULL pointer dereference in pagecache_get_page
Date: Tue, 26 Apr 2022 14:06:41 -0700 [thread overview]
Message-ID: <20220426140641.cc78a429e1fa32ed0e15520b@linux-foundation.org> (raw)
In-Reply-To: <YmfgqKcMmstgfz+0@casper.infradead.org>
On Tue, 26 Apr 2022 13:08:08 +0100 Matthew Wilcox <willy@infradead.org> wrote:
> On Tue, Apr 26, 2022 at 04:25:48PM +0800, Wan Jiabing wrote:
> > Fix following coccicheck error:
> > mm/folio-compat.c:128:17-21: ERROR: folio is NULL but dereferenced.
> > folio = __filemap_get_folio(mapping, index, fgp_flags, gfp);
> > - if ((fgp_flags & FGP_HEAD) || !folio || xa_is_value(folio))
> > + if (!folio)
> > + return NULL;
> > + if ((fgp_flags & FGP_HEAD) || xa_is_value(folio))
> > return &folio->page;
>
> That doesn't dereference the folio. Coccicheck is wrong.
Doing
return &(0->page);
is a rather obscure way of doing `return NULL;'.
I agree the patch doesn't fix anything, but it results in saner-looking code?
next prev parent reply other threads:[~2022-04-26 21:06 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-26 8:25 Wan Jiabing
2022-04-26 12:08 ` Matthew Wilcox
2022-04-26 21:06 ` Andrew Morton [this message]
2022-04-26 21:17 ` Matthew Wilcox
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