linux-kernel - Re: [PATCH] scsi: sd: Jump to out_free_index if device_add{,

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Date:   Tue, 29 Mar 2022 10:28:24 +0200
From:   "Fabio M. De Francesco" <fmdefrancesco@...il.com>
To:     Dan Carpenter <dan.carpenter@...cle.com>
Cc:     axboe@...nel.dk, linux-block@...r.kernel.org,
        linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        linux-scsi@...r.kernel.org,
        syzbot+f08c77040fa163a75a46@...kaller.appspotmail.com
Subject: Re: [PATCH] scsi: sd: Jump to out_free_index if device_add{,_disk}() fail

On marted? 29 marzo 2022 09:57:53 CEST Dan Carpenter wrote:
> On Tue, Mar 29, 2022 at 10:47:45AM +0300, Dan Carpenter wrote:
> > No, this patch is wrong.  That is supposed to be freed in scsi_disk_release()
> > but apparently that's not getting called.  Is the ref counting off?
> > 
> 
> Yeah.  The device_add() needs a matching device_del().
> 
> regards,
> dan carpenter
> 
Thanks, Dan.

I've just just checked other similar code and saw the following pattern 
whenever we have an error:

device_del(dev);
put_device(dev);

Therefore, I suppose that you are suggesting the following simple change:

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index a390679cf458..13d96d0f9dde 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -3474,6 +3474,7 @@ static int sd_probe(struct device *dev)
 
        error = device_add_disk(dev, gd, NULL);
        if (error) {
+               device_del(&sdkp->disk_dev);
                put_device(&sdkp->disk_dev);
                goto out;
        }

Did I get it?

Regards,

Fabio