2023-06-30 03:06:22

by Tuo Li

Subject: [PATCH] scsi: lpfc: Fix a possible data race in lpfc_unregister_fcf_rescan()

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 <[email protected]>
Signed-off-by: Tuo Li <[email protected]>
---
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 5ba3a9ad9501..9d2feb69cae7 100644
--- a/drivers/scsi/lpfc/lpfc_hbadisc.c
+++ b/drivers/scsi/lpfc/lpfc_hbadisc.c
@@ -6961,7 +6961,9 @@ 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

2023-07-04 16:27:50

by Justin Tee

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

Hi Tuo,

Looks good.

Reviewed-by: Justin Tee <[email protected]>

Thanks,
Justin

On Thu, Jun 29, 2023 at 8:03 PM Tuo Li <[email protected]> wrote:
>
> 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 <[email protected]>
> Signed-off-by: Tuo Li <[email protected]>
> ---
> 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 5ba3a9ad9501..9d2feb69cae7 100644
> --- a/drivers/scsi/lpfc/lpfc_hbadisc.c
> +++ b/drivers/scsi/lpfc/lpfc_hbadisc.c
> @@ -6961,7 +6961,9 @@ 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
>

2023-07-05 14:55:11

by Laurence Oberman

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

On Fri, 2023-06-30 at 10:47 +0800, Tuo Li wrote:
> 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 <[email protected]>
> Signed-off-by: Tuo Li <[email protected]>
> ---
>  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 5ba3a9ad9501..9d2feb69cae7 100644
> --- a/drivers/scsi/lpfc/lpfc_hbadisc.c
> +++ b/drivers/scsi/lpfc/lpfc_hbadisc.c
> @@ -6961,7 +6961,9 @@ 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;
>  
>         /*

This makes sense and looks good to me
Reviewed-by: Laurence Oberman <[email protected]>