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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Dan Carpenter <dan.carpenter@oracle.com>,
        Johannes Thumshirn <jthumshirn@suse.de>,
        Matthew Wilcox <mawilcox@microsoft.com>,
        "Martin K. Petersen" <martin.petersen@oracle.com>,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 4.9 54/96] scsi: sym53c8xx_2: iterator underflow in sym_getsync()
Date:   Thu, 24 May 2018 11:38:37 +0200
Message-Id: <20180524093608.611763912@linuxfoundation.org>
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4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Dan Carpenter <dan.carpenter@oracle.com>

[ Upstream commit e6f791d95313c85f3dd4a26141e28e50ae9aa0ae ]

We wanted to exit the loop with "div" set to zero, but instead, if we
don't hit the break then "div" is -1 when we finish the loop.  It leads
to an array underflow a few lines later.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Acked-by: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/scsi/sym53c8xx_2/sym_hipd.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/scsi/sym53c8xx_2/sym_hipd.c
+++ b/drivers/scsi/sym53c8xx_2/sym_hipd.c
@@ -536,7 +536,7 @@ sym_getsync(struct sym_hcb *np, u_char d
 	 *  Look for the greatest clock divisor that allows an 
 	 *  input speed faster than the period.
 	 */
-	while (div-- > 0)
+	while (--div > 0)
 		if (kpc >= (div_10M[div] << 2)) break;
 
 	/*