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Message-ID: <d656179616d61623e1c2b45c1df219c0693749a1.camel@mediatek.com>
Subject: Re: [PATCH] scsi: sd: fix crashes in sd_resume_runtime
From:   Stanley Chu <stanley.chu@mediatek.com>
To:     Miles Chen <miles.chen@mediatek.com>,
        "James E . J . Bottomley" <jejb@linux.ibm.com>,
        "Martin K . Petersen" <martin.petersen@oracle.com>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Bart Van Assche <bvanassche@acm.org>,
        Martin Kepplinger <martink@posteo.de>
CC:     <linux-scsi@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-mediatek@lists.infradead.org>, <wsd_upstream@mediatek.com>
Date:   Fri, 15 Oct 2021 21:33:08 +0800
In-Reply-To: <20211015074654.19615-1-miles.chen@mediatek.com>
References: <20211015074654.19615-1-miles.chen@mediatek.com>
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Hi Miles,

On Fri, 2021-10-15 at 15:46 +0800, Miles Chen wrote:
> After merging commit ed4246d37f3b ("scsi: sd: REQUEST SENSE for
> BLIST_IGN_MEDIA_CHANGE devices in runtime_resume()"), I hit the
> following crash on my device.
> 
> static int sd_resume_runtime(struct device *dev)
> {
>         struct scsi_disk *sdkp = dev_get_drvdata(dev);
>         struct scsi_device *sdp = sdkp->device; // sdkp == NULL and
> crash
> 
>         if (sdp->ignore_media_change) {
> 	...
> }
> 
> I checked sd_resume() and found that sdkp is possbile to be NULL, and
> there is a null pointer test in sd_resume() for this case.
> To fix this crash, follow sd_resume() to test if sdkp is NULL
> before dereferencing it.


LGTM.

Reviewed-by: Stanley Chu <stanley.chu@mediatek.com>