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From:   Tuo Li <islituo@gmail.com>
To:     sathya.prakash@broadcom.com, sreekanth.reddy@broadcom.com,
        suganath-prabu.subramani@broadcom.com, jejb@linux.ibm.com,
        martin.petersen@oracle.com
Cc:     MPT-FusionLinux.pdl@broadcom.com, linux-scsi@vger.kernel.org,
        linux-kernel@vger.kernel.org, baijiaju1990@gmail.com,
        Tuo Li <islituo@gmail.com>, TOTE Robot <oslab@tsinghua.edu.cn>
Subject: [PATCH] scsi: mpt3sas: Fix a possible divide-by-zero bug in base_mod64()
Date:   Wed, 11 Aug 2021 06:24:39 -0700
Message-Id: <20210811132439.10370-1-islituo@gmail.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

The variable divisor is checked in:
  if (!divisor)

This indicates that divisor can be NULL.
If so, a divide-by-zero bug will occur:
  remainder = do_div(dividend, divisor);

To fix the possible bug, the function returns 0 when divisor is zero.

Reported-by: TOTE Robot <oslab@tsinghua.edu.cn>
Signed-off-by: Tuo Li <islituo@gmail.com>
---
 drivers/scsi/mpt3sas/mpt3sas_base.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/mpt3sas/mpt3sas_base.c b/drivers/scsi/mpt3sas/mpt3sas_base.c
index 19b1c0cf5f2a..3550998ea38b 100644
--- a/drivers/scsi/mpt3sas/mpt3sas_base.c
+++ b/drivers/scsi/mpt3sas/mpt3sas_base.c
@@ -1594,8 +1594,10 @@ static u32 base_mod64(u64 dividend, u32 divisor)
 {
 	u32 remainder;
 
-	if (!divisor)
+	if (!divisor) {
 		pr_err("mpt3sas: DIVISOR is zero, in div fn\n");
+		return 0;
+	}
 	remainder = do_div(dividend, divisor);
 	return remainder;
 }
-- 
2.25.1