linux-kernel - [PATCH] sym53c8xx: Avoid undefined behaviour in drivers/scsi/sym53c8xx_2/sym

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Message-ID: <20170810190849.GA12659@p100.box>
Date:   Thu, 10 Aug 2017 21:08:49 +0200
From:   Helge Deller <deller@....de>
To:     linux-scsi@...r.kernel.org,
        James Bottomley <James.Bottomley@...senPartnership.com>,
        linux-kernel@...r.kernel.org
Cc:     linux-parisc@...r.kernel.org
Subject: [PATCH] sym53c8xx: Avoid undefined behaviour in
 drivers/scsi/sym53c8xx_2/sym_hipd.c:762

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 dev64_ul().

Signed-off-by: Helge Deller <deller@....de>

diff --git a/drivers/scsi/sym53c8xx_2/sym_hipd.c b/drivers/scsi/sym53c8xx_2/sym_hipd.c
index 6b349e3..15ff285a9 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;
 
 	/*