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SubjectRe: [PATCH 2.6.19.2] SCSI sd: udev accessing an uninitialized scsi_disk results in a crash
On Fri, 2 Feb 2007 17:34:56 +0530
Nagendra Singh Tomar <nagendra_tomar@adaptec.com> wrote:

> Hi,
> sd_probe() calls class_device_add() even before initializing the
> sdkp->device variable. class_device_add() eventually results in the user mode
> udev program to be called. udev program can read the the allow_restart
> attribute of the newly created scsi device. This is resulting in a crash as
> the show function for allow_restart (i.e sd_show_allow_restart) returns the
> attribute value by reading the sdkp->device->allow_restart variable. As the
> sdkp->device is not initialized before calling the user mode hotplug helper,
> this results in a crash.
> The patch below solves it by calling class_device_add() only after the
> necessary fields in the scsi_disk structure are initialized properly.
>
>
>
> --- linux-2.6.19.2/drivers/scsi/sd.c.orig 2007-02-02 17:03:03.000000000 +0530
> +++ linux-2.6.19.2/drivers/scsi/sd.c 2007-02-02 17:04:04.000000000 +0530
> @@ -1646,16 +1646,6 @@ static int sd_probe(struct device *dev)
> if (error)
> goto out_put;
>
> - class_device_initialize(&sdkp->cdev);
> - sdkp->cdev.dev = &sdp->sdev_gendev;
> - sdkp->cdev.class = &sd_disk_class;
> - strncpy(sdkp->cdev.class_id, sdp->sdev_gendev.bus_id, BUS_ID_SIZE);
> -
> - if (class_device_add(&sdkp->cdev))
> - goto out_put;
> -
> - get_device(&sdp->sdev_gendev);
> -
> sdkp->device = sdp;
> sdkp->driver = &sd_template;
> sdkp->disk = gd;
> @@ -1669,6 +1659,16 @@ static int sd_probe(struct device *dev)
> sdp->timeout = SD_MOD_TIMEOUT;
> }
>
> + class_device_initialize(&sdkp->cdev);
> + sdkp->cdev.dev = &sdp->sdev_gendev;
> + sdkp->cdev.class = &sd_disk_class;
> + strncpy(sdkp->cdev.class_id, sdp->sdev_gendev.bus_id, BUS_ID_SIZE);
> +
> + if (class_device_add(&sdkp->cdev))
> + goto out_put;
> +
> + get_device(&sdp->sdev_gendev);
> +
> gd->major = sd_major((index & 0xf0) >> 4);
> gd->first_minor = ((index & 0xf) << 4) | (index & 0xfff00);
> gd->minors = 16;

Thanks - I'll queue this up for 2.6.20 also.
-
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