From: Jason Gunthorpe <jgg@ziepe.ca>
To: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Matthew Wilcox <willy@infradead.org>,
Wang Hai <wanghai38@huawei.com>,
cl@linux.com, penberg@kernel.org, rientjes@google.com,
iamjoonsoo.kim@lge.com, akpm@linux-foundation.org,
khlebnikov@yandex-team.ru, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: kobject_init_and_add is easy to misuse
Date: Wed, 3 Jun 2020 15:36:50 -0300 [thread overview]
Message-ID: <20200603183650.GI6578@ziepe.ca> (raw)
In-Reply-To: <1591207475.4462.41.camel@HansenPartnership.com>
On Wed, Jun 03, 2020 at 11:04:35AM -0700, James Bottomley wrote:
> On Tue, 2020-06-02 at 21:22 -0300, Jason Gunthorpe wrote:
> > On Tue, Jun 02, 2020 at 02:51:10PM -0700, James Bottomley wrote:
> >
> > > My first thought was "what? I got suckered into creating a patch",
> > > thanks ;-) But now I look, all the error paths do unwind back to
> > > the initial state, so kfree() on error looks to be completely
> > > correct.
> >
> > It doesn't fully unwind if the kobject is put into a kset, then
> > another thread can get the kref during kset_find_obj() and kfree()
> > won't wait for the kref to go to 0. It must use put.
>
> That does seem a bit contrived: the only failure kobject_add_internal()
> can get after kobj_kset_join() is from directory creation. If
> directory creation fails, no name appears in sysfs and no event for the
> name is sent, how did another thread get the name to pass in to
> kset_find_obj()?
The other thread just guesses in a hostile way?
Eg it looks like the iommu stuff just feeds in user data to
kobj_kset_join().
Jason
next prev parent reply other threads:[~2020-06-03 18:36 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-02 11:50 [PATCH] mm/slub: fix a memory leak in sysfs_slab_add() Wang Hai
2020-06-02 12:10 ` kobject_init_and_add is easy to misuse Matthew Wilcox
2020-06-02 13:48 ` Konstantin Khlebnikov
2020-06-02 14:04 ` Greg Kroah-Hartman
2020-06-02 14:57 ` Matthew Wilcox
2020-06-02 15:25 ` James Bottomley
2020-06-02 17:36 ` Greg Kroah-Hartman
2020-06-02 19:54 ` James Bottomley
2020-06-02 20:07 ` Greg Kroah-Hartman
2020-06-02 21:51 ` James Bottomley
2020-06-03 0:04 ` James Bottomley
2020-06-03 0:22 ` Jason Gunthorpe
2020-06-03 18:04 ` James Bottomley
2020-06-03 18:36 ` Jason Gunthorpe [this message]
2020-06-03 19:02 ` James Bottomley
2020-06-03 19:30 ` Jason Gunthorpe
2020-06-03 20:56 ` James Bottomley
2020-06-04 0:23 ` Jason Gunthorpe
2020-06-02 19:46 ` Jason Gunthorpe
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