Re: [PATCH 06/12] qla4xxx: fixed NULL pointer dereference in eh_device_reset

[Mike Christie <michaelc@cs.wisc.edu>]

On 04/06/2010 05:14 AM, Ravi Anand wrote:
> From: Vikas Chaudhary<vikas.chaudhary@qlogic.com>
>
> Created variables to reference h, b, t, l, because if
> scsi passthru command completes within eh_device_reset,
> the cmd structure may no longer be valid.


> @@ -1587,16 +1587,34 @@ static int qla4xxx_eh_wait_for_commands(struct scsi_qla_host *ha,
>    **/
>   static int qla4xxx_eh_device_reset(struct scsi_cmnd *cmd)
>   {
> -	struct scsi_qla_host *ha = to_qla_host(cmd->device->host);
> -	struct ddb_entry *ddb_entry = cmd->device->hostdata;
> +	struct scsi_qla_host *ha;
> +	struct ddb_entry *ddb_entry;
>   	int ret = FAILED, stat;
> +	struct Scsi_Host *h;
> +	unsigned int b, t, l;
> +
> +	if (cmd == NULL) {
> +		DEBUG2(printk(KERN_INFO "%s: **** SCSI mid-layer passing in"
> +				" NULL cmd DEVICE RESET - cmd already"
> +				" completed.\n", __func__));
> +		return SUCCESS;
> +	}
>
> -	if (!ddb_entry)
> -		return ret;
> +	h = cmd->device->host;
> +	b = cmd->device->channel;
> +	t = cmd->device->id;
> +	l = cmd->device->lun;
> +	ha = to_qla_host(h);
> +	ddb_entry = cmd->device->hostdata;


Could it complete normally while you are accessing the cmd above still?