From: "Seunghui Lee" <sh043.lee@samsung.com>
To: "'Greg KH'" <gregkh@linuxfoundation.org>
Cc: <linux-mmc@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
<ulf.hansson@linaro.org>, <avri.altman@wdc.com>,
<grant.jung@samsung.com>, <jt77.jang@samsung.com>,
<dh0421.hwang@samsung.com>, <junwoo80.lee@samsung.com>,
<jangsub.yi@samsung.com>, <cw9316.lee@samsung.com>,
<sh8267.baek@samsung.com>, <wkon.kim@samsung.com>
Subject: RE: [PATCH] mmc: core: Fix null pointer dereference in bus_shutdown
Date: Fri, 26 Jan 2024 14:16:57 +0900 [thread overview]
Message-ID: <011a01da5016$e23f41f0$a6bdc5d0$@samsung.com> (raw)
In-Reply-To: <2024011945-studio-smitten-300e@gregkh>
> -----Original Message-----
> From: Greg KH <gregkh@linuxfoundation.org>
> Sent: Friday, January 19, 2024 5:21 PM
> To: Seunghui Lee <sh043.lee@samsung.com>
> Cc: linux-mmc@vger.kernel.org; linux-kernel@vger.kernel.org;
> ulf.hansson@linaro.org; avri.altman@wdc.com; grant.jung@samsung.com;
> jt77.jang@samsung.com; dh0421.hwang@samsung.com; junwoo80.lee@samsung.com;
> jangsub.yi@samsung.com; cw9316.lee@samsung.com; sh8267.baek@samsung.com;
> wkon.kim@samsung.com
> Subject: Re: [PATCH] mmc: core: Fix null pointer dereference in
> bus_shutdown
>
> On Fri, Jan 19, 2024 at 04:32:47PM +0900, Seunghui Lee wrote:
> > When shutting down removable device,
> > it can be occurred null pointer dereference.
>
> How?
>
> And please wrap your lines properly.
>
> > To prevent null pointer dereference,
> > At first, check null pointer.
> > Next, block rescan worker to scan removable device during shutdown.
>
> Why do two things?
>
> >
> > Signed-off-by: Seunghui Lee <sh043.lee@samsung.com>
> > ---
> > drivers/mmc/core/bus.c | 10 +++++++++-
> > 1 file changed, 9 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/mmc/core/bus.c b/drivers/mmc/core/bus.c index
> > 0af96548e7da..4f370a6577aa 100644
> > --- a/drivers/mmc/core/bus.c
> > +++ b/drivers/mmc/core/bus.c
> > @@ -143,9 +143,17 @@ static void mmc_bus_shutdown(struct device *dev)
> > {
> > struct mmc_driver *drv = to_mmc_driver(dev->driver);
> > struct mmc_card *card = mmc_dev_to_card(dev);
> > - struct mmc_host *host = card->host;
> > + struct mmc_host *host;
> > int ret;
> >
> > + if (!drv || !card) {
> > + pr_debug("%s: drv or card is NULL.\n", dev_name(dev));
>
> What is this going to help with? And why not use dev_dbg()?
>
> How can drv ever be NULL? That looks impossible to me based on just the
> code shown here.
>
> > + return;
> > + }
> > +
> > + host = card->host;
>
> Why is this change needed? This line can go back to the top just fine,
> right?
>
> > + host->rescan_disable = 1;
>
> Shouldn't this be a separate change? And what happens if the check for
> this is right before you set it? Where is the locking to prevent the
> issue you are attempting to solve?
>
> thanks,
>
> greg k-h
I've checked the issue again.
This patch is not the proper solution.
I'll reject this patch.
Hi, Thank you for your comment.
prev parent reply other threads:[~2024-01-26 5:17 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20240119073011epcas1p1841e79c8f673c3c69ef696edc9eb47b0@epcas1p1.samsung.com>
2024-01-19 7:32 ` [PATCH] mmc: core: Fix null pointer dereference in bus_shutdown Seunghui Lee
2024-01-19 8:20 ` Greg KH
2024-01-26 5:16 ` Seunghui Lee [this message]
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