[PATCH 6.1.y] scsi: lpfc: Fix a possible data race in lpfc_unregister_fcf_rescan()

[PATCH 6.1.y] scsi: lpfc: Fix a possible data race in lpfc_unregister_fcf_rescan()

[jetlan9]

From: Tuo Li <islituo@gmail.com>

[ Upstream commit 0e881c0a4b6146b7e856735226208f48251facd8 ]

The variable phba->fcf.fcf_flag is often protected by the lock
phba->hbalock() when is accessed. Here is an example in
lpfc_unregister_fcf_rescan():

  spin_lock_irq(&phba->hbalock);
  phba->fcf.fcf_flag |= FCF_INIT_DISC;
  spin_unlock_irq(&phba->hbalock);

However, in the same function, phba->fcf.fcf_flag is assigned with 0
without holding the lock, and thus can cause a data race:

  phba->fcf.fcf_flag = 0;

To fix this possible data race, a lock and unlock pair is added when
accessing the variable phba->fcf.fcf_flag.

Reported-by: BassCheck <bass@buaa.edu.cn>
Signed-off-by: Tuo Li <islituo@gmail.com>
Link: https://lore.kernel.org/r/20230630024748.1035993-1-islituo@gmail.com
Reviewed-by: Justin Tee <justin.tee@broadcom.com>
Reviewed-by: Laurence Oberman <loberman@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Wenshan Lan <jetlan9@163.com>
---
 drivers/scsi/lpfc/lpfc_hbadisc.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/scsi/lpfc/lpfc_hbadisc.c b/drivers/scsi/lpfc/lpfc_hbadisc.c
index d3a5f10b8b83..57be02f8d5c1 100644
--- a/drivers/scsi/lpfc/lpfc_hbadisc.c
+++ b/drivers/scsi/lpfc/lpfc_hbadisc.c
@@ -6942,7 +6942,9 @@ lpfc_unregister_fcf_rescan(struct lpfc_hba *phba)
 	if (rc)
 		return;
 	/* Reset HBA FCF states after successful unregister FCF */
+	spin_lock_irq(&phba->hbalock);
 	phba->fcf.fcf_flag = 0;
+	spin_unlock_irq(&phba->hbalock);
 	phba->fcf.current_rec.flag = 0;
 
 	/*
-- 
2.34.1

Re: [PATCH 6.1.y] scsi: lpfc: Fix a possible data race in lpfc_unregister_fcf_rescan()

[Sasha Levin]

[ Sasha's backport helper bot ]

Hi,

✅ All tests passed successfully. No issues detected.
No action required from the submitter.

The upstream commit SHA1 provided is correct: 0e881c0a4b6146b7e856735226208f48251facd8

WARNING: Author mismatch between patch and upstream commit:
Backport author: jetlan9@163.com
Commit author: Tuo Li<islituo@gmail.com>

Status in newer kernel trees:
6.13.y | Present (exact SHA1)
6.12.y | Present (exact SHA1)
6.6.y | Present (exact SHA1)

Note: The patch differs from the upstream commit:
---
1:  0e881c0a4b614 ! 1:  81de9644dc48c scsi: lpfc: Fix a possible data race in lpfc_unregister_fcf_rescan()
    @@ Metadata
      ## Commit message ##
         scsi: lpfc: Fix a possible data race in lpfc_unregister_fcf_rescan()
     
    +    [ Upstream commit 0e881c0a4b6146b7e856735226208f48251facd8 ]
    +
         The variable phba->fcf.fcf_flag is often protected by the lock
         phba->hbalock() when is accessed. Here is an example in
         lpfc_unregister_fcf_rescan():
    @@ Commit message
         Reviewed-by: Justin Tee <justin.tee@broadcom.com>
         Reviewed-by: Laurence Oberman <loberman@redhat.com>
         Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
    +    Signed-off-by: Wenshan Lan <jetlan9@163.com>
     
      ## drivers/scsi/lpfc/lpfc_hbadisc.c ##
     @@ drivers/scsi/lpfc/lpfc_hbadisc.c: lpfc_unregister_fcf_rescan(struct lpfc_hba *phba)
---

Results of testing on various branches:

| Branch                    | Patch Apply | Build Test |
|---------------------------|-------------|------------|
| stable/linux-6.1.y        |  Success    |  Success   |