From: Christoph Hellwig <hch@infradead.org>
To: Jeff Layton <jlayton@redhat.com>
Cc: bfields@fieldses.org, hch@infradead.org, gartim@gmail.com,
linux-nfs@vger.kernel.org
Subject: Re: [PATCH] nfsd: when reusing an existing repcache entry, unhash it first
Date: Tue, 3 Dec 2013 02:25:17 -0800 [thread overview]
Message-ID: <20131203102517.GA12576@infradead.org> (raw)
In-Reply-To: <1386015979-27511-1-git-send-email-jlayton@redhat.com>
On Mon, Dec 02, 2013 at 03:26:19PM -0500, Jeff Layton wrote:
> The DRC code will attempt to reuse an existing, expired cache entry in
> preference to allocating a new one. It'll then search the cache, and if
> it gets a hit it'll then free the cache entry that it was going to
> reuse.
>
> The cache code doesn't unhash the entry that it's going to reuse
> however, so it's possible for it end up designating an entry for reuse
> and then subsequently freeing the same entry after it finds it. This
> leads it to a later use-after-free situation and usually some list
> corruption warnings or an oops.
>
> Fix this by simply unhashing the entry that we intend to reuse. That
> will mean that it's not findable via a search and should prevent this
> situation from occurring.
The fix looks reasonable to me,
Reviewed-by: Christoph Hellwig <hch@lst.de>
Btw, it seems like this code would benefit from being converted to
the list_lru structure.
next prev parent reply other threads:[~2013-12-03 10:25 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-02 20:26 [PATCH] nfsd: when reusing an existing repcache entry, unhash it first Jeff Layton
2013-12-03 10:25 ` Christoph Hellwig [this message]
2013-12-03 18:21 ` Jeff Layton
2013-12-04 8:33 ` Christoph Hellwig
2013-12-04 12:54 ` Jeff Layton
2013-12-04 13:09 ` Christoph Hellwig
2013-12-04 13:31 ` Jeff Layton
2013-12-04 13:40 ` Christoph Hellwig
2013-12-04 13:45 ` Jeff Layton
2013-12-04 13:54 ` Christoph Hellwig
2013-12-04 14:15 ` Jeff Layton
2013-12-04 14:25 ` J. Bruce Fields
2013-12-04 17:06 ` Jeff Layton
2013-12-04 17:06 ` Christoph Hellwig
2013-12-04 18:43 ` Jeff Layton
2013-12-03 15:50 ` J. Bruce Fields
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