From: Helge Deller <deller@gmx.de>
Date: Thu, 10 Aug 2017 21:08:49 +0200
Subject: [PATCH] scsi: sym53c8xx: Avoid undefined behaviour
References: bsc#1077989
Git-commit: c0e8ed04b32307c192bcf37f5810e490e4d2739e
Patch-mainline: v4.14-rc1

On parisc I see this UBSAN warning with a sym53c896:

 UBSAN: Undefined behaviour in ./drivers/scsi/sym53c8xx_2/sym_hipd.c:762:24
 index -1903078336 is out of range for type 'u32 [7]'

Avoid this warning by switching to div64_ul().

[mkp: fix typo]

Signed-off-by: Helge Deller <deller@gmx.de>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Hannes Reinecke <hare@suse.de>
---
 drivers/scsi/sym53c8xx_2/sym_hipd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/scsi/sym53c8xx_2/sym_hipd.c b/drivers/scsi/sym53c8xx_2/sym_hipd.c
index 6b349e301869..15ff285a9f8f 100644
--- a/drivers/scsi/sym53c8xx_2/sym_hipd.c
+++ b/drivers/scsi/sym53c8xx_2/sym_hipd.c
@@ -759,7 +759,7 @@ static int sym_prepare_setting(struct Scsi_Host *shost, struct sym_hcb *np, stru
 	/*
 	 * Maximum synchronous period factor supported by the chip.
 	 */
-	period = (11 * div_10M[np->clock_divn - 1]) / (4 * np->clock_khz);
+	period = div64_ul(11 * div_10M[np->clock_divn - 1], 4 * np->clock_khz);
 	np->maxsync = period > 2540 ? 254 : period / 10;
 
 	/*
-- 
2.12.3