Re: [PATCH v3 03/15] scsi: ufs: verify command tag validity

[Akinobu Mita]

2015-09-02 19:13 GMT+09:00 Yaniv Gardi <ygardi@xxxxxxxxxxxxxx>:
> A race condition appear to exist between request completion when
> scsi_done() is called to end the request and set the tag back to
> -1 (at blk_queue_end_tag() scsi_end_request), and scsi layer error
> handling which aborts the command and reuses it to request sense
> data. Sending the request sense is done with tag which was set to -1
> and so it is invalid.
> Assert command tag passed from scsi layer is valid.
>
> Signed-off-by: Gilad Broner <gbroner@xxxxxxxxxxxxxx>
> Signed-off-by: Yaniv Gardi <ygardi@xxxxxxxxxxxxxx>
>
> ---
>  drivers/scsi/ufs/ufshcd.c | 24 ++++++++++++++++++++++--
>  1 file changed, 22 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index 2d3ebca..8860a57 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -190,6 +190,10 @@ static int ufshcd_config_pwr_mode(struct ufs_hba *hba,
>                 struct ufs_pa_layer_attr *desired_pwr_mode);
>  static int ufshcd_change_power_mode(struct ufs_hba *hba,
>                              struct ufs_pa_layer_attr *pwr_mode);
> +static inline bool ufshcd_valid_tag(struct ufs_hba *hba, int tag)
> +{
> +       return tag >= 0 && tag < hba->nutrs;
> +}
>
>  static inline int ufshcd_enable_irq(struct ufs_hba *hba)
>  {
> @@ -1310,6 +1314,12 @@ static int ufshcd_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *cmd)
>         hba = shost_priv(host);
>
>         tag = cmd->request->tag;
> +       if (!ufshcd_valid_tag(hba, tag)) {
> +               dev_err(hba->dev,
> +                       "%s: invalid command tag %d: cmd=0x%p, cmd->request=0x%p",
> +                       __func__, tag, cmd, cmd->request);
> +               BUG();
> +       }

Is it better to avoid BUG() by WARN_ON() and return if possible?
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