linux-kernel - [PATCH AUTOSEL 4.19] scsi: lpfc: Fix a possible data race in lpfc_unregister_fcf

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Message-Id: <20230803130358.641808-1-sashal@kernel.org>
Date:   Thu,  3 Aug 2023 09:03:58 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Tuo Li <islituo@...il.com>, BassCheck <bass@...a.edu.cn>,
        Justin Tee <justin.tee@...adcom.com>,
        Laurence Oberman <loberman@...hat.com>,
        "Martin K . Petersen" <martin.petersen@...cle.com>,
        Sasha Levin <sashal@...nel.org>, james.smart@...adcom.com,
        dick.kennedy@...adcom.com, jejb@...ux.ibm.com,
        linux-scsi@...r.kernel.org
Subject: [PATCH AUTOSEL 4.19] scsi: lpfc: Fix a possible data race in lpfc_unregister_fcf_rescan()

From: Tuo Li <islituo@...il.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@...a.edu.cn>
Signed-off-by: Tuo Li <islituo@...il.com>
Link: https://lore.kernel.org/r/20230630024748.1035993-1-islituo@gmail.com
Reviewed-by: Justin Tee <justin.tee@...adcom.com>
Reviewed-by: Laurence Oberman <loberman@...hat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@...cle.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 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 5d657178c2b98..8be1c0b4e2a86 100644
--- a/drivers/scsi/lpfc/lpfc_hbadisc.c
+++ b/drivers/scsi/lpfc/lpfc_hbadisc.c
@@ -6443,7 +6443,9 @@ 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;
 
 	/*
-- 
2.40.1