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    SubjectRe: [PATCH v3 03/15] scsi: ufs: verify command tag validity
    From
    2015-09-02 19:13 GMT+09:00 Yaniv Gardi <ygardi@codeaurora.org>:
    > 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@codeaurora.org>
    > Signed-off-by: Yaniv Gardi <ygardi@codeaurora.org>
    >
    > ---
    > 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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