Re: [PATCH v2] scsi: storvsc: Support manual scans for all Hyper-V targets

[Laurence Oberman <loberman@redhat.com>]

On Thu, 2026-07-23 at 16:51 +0000, sashiko-bot@kernel.org wrote:
> Thank you for your contribution! Sashiko AI review found 2 potential
> issue(s) to consider:
> 
> Pre-existing issues:
> - [High] Kernel panic in fc_eh_timed_out() due to missing NULL check
> for fc_rport, contradicting the v2 changelog claim.
> - [High] Use-After-Free race condition in fc_user_scan_tgt due to
> unpinned rport pointer.
> --
> 
> --- Patch [1]: [PATCH v2] scsi: storvsc: Support manual scans for all
> Hyper-V targets ---
> commit 7a84d34942989f4df1a7195141939c24f221c9ea
> Author: Laurence Oberman <loberman@redhat.com>
> 
> scsi: storvsc: Support manual scans for all Hyper-V targets
> 
> This patch provides a storvsc-specific user_scan callback that uses
> the
> exported scsi_scan_target() interface to allow explicit scanning of
> targets
> without requiring synthetic fc_rports for each target.
> 
> > ---
> > Changes in v2:
> > - Replace the private, unexported scsi_scan_host_selected() helper
> > with
> >   the exported scsi_scan_target() interface.
> > - Preserve wildcard channel and target scan behavior.
> > - Verify that storvsc_eh_timed_out() does not use the FC error-
> > handler
> >   helpers; the reported missing-rport dereference is not present.
> 
> [Severity: High]
> This isn't a bug introduced by this patch, but is the v2 changelog
> accurate
> regarding storvsc_eh_timed_out()?
> 
> Looking at storvsc_eh_timed_out() in drivers/scsi/storvsc_drv.c, it
> appears
> to explicitly route I/O timeouts to the FC transport error handler:
> 
> if (scmnd->device->host->transportt == fc_transport_template)
>         return fc_eh_timed_out(scmnd);
> 
> When fc_eh_timed_out() handles this, it extracts the fc_rport
> pointer:
> 
> struct fc_rport *rport = starget_to_rport(scsi_target(scmd->device));
> if (rport->port_state == FC_PORTSTATE_BLOCKED)
> 
> Because storvsc targets are created without an intermediate fc_rport
> parent,
> starget_to_rport() returns NULL. Does this mean fc_eh_timed_out()
> will
> immediately dereference a NULL pointer during an I/O timeout?
> 
> 
> As a related observation on the FC transport layer scan paths:
> 
> [Severity: High]
> This is a pre-existing issue, but does fc_user_scan_tgt() have a race
> condition that could lead to a use-after-free?
> 
> In drivers/scsi/scsi_transport_fc.c:fc_user_scan_tgt(), the host lock
> is
> dropped before scanning the target:
> 
> spin_unlock_irqrestore(shost->host_lock, flags);
> scsi_scan_target(&rport->dev, channel, id, lun,
>                  SCSI_SCAN_MANUAL);
> 
> If a concurrent FC link down event or port removal triggers
> fc_rport_final_delete(), can the rport device be removed and freed
> before
> or during the scsi_scan_target() execution? If so, should a reference
> be
> acquired on rport->dev prior to dropping the lock?

I do not see any of F/C related calls in what I modified or in the code
I worked on so for me v2 is the correct and final version of this.

Thanks
Laurence