From: Dan Carpenter <dan.carpenter@oracle.com>
To: Ming Lei <ming.lei@redhat.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>,
linux-block@vger.kernel.org
Subject: Re: [bug report] zram: avoid race between zram_remove and disksize_store
Date: Fri, 5 Nov 2021 12:18:14 +0300 [thread overview]
Message-ID: <20211105091638.GA2026@kadam> (raw)
In-Reply-To: <YYR5fmwmfvfQzWuZ@T590>
On Fri, Nov 05, 2021 at 08:23:26AM +0800, Ming Lei wrote:
> > --> 2044 zram_reset_device(zram);
> >
> > This double frees it.
>
> No.
>
> Inside zram_reset_device(), if init_done()(zram->disksize) is zero, zram_reset_device()
> returns immediately, otherwise zram->disksize is cleared and zram_meta_free()
> is run in zram_reset_device(). Meantime zram->init_lock protects the
> reset and disksize_store().
>
> The 2nd zram_reset_device() can only reset device if disksize_store() sets new
> zram->disksize and allocates new meta after the 1st zram_reset_device().
>
> Seems smatch static checker need to be improved to cover this case?
Yep. It's a bug in Smatch. It's supposed to parse this correctly.
I will investigate. Thanks!
regards,
dan carpenter
prev parent reply other threads:[~2021-11-05 9:18 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-04 11:48 [bug report] zram: avoid race between zram_remove and disksize_store Dan Carpenter
2021-11-04 11:49 ` Dan Carpenter
2021-11-05 0:23 ` Ming Lei
2021-11-05 9:18 ` Dan Carpenter [this message]
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