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Groups > linux.kernel > #1708971 > unrolled thread

[PATCH] sym53c8xx: Avoid undefined behaviour in drivers/scsi/sym53c8xx_2/sym_hipd.c:762

Started byHelge Deller <deller@gmx.de>
First post2017-08-10 21:10 +0200
Last post2017-08-11 09:30 +0200
Articles 2 — 2 participants

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  [PATCH] sym53c8xx: Avoid undefined behaviour in  drivers/scsi/sym53c8xx_2/sym_hipd.c:762 Helge Deller <deller@gmx.de> - 2017-08-10 21:10 +0200
    Re: [PATCH] sym53c8xx: Avoid undefined behaviour in  drivers/scsi/sym53c8xx_2/sym_hipd.c:762 Johannes Thumshirn <jthumshirn@suse.de> - 2017-08-11 09:30 +0200

#1708971 — [PATCH] sym53c8xx: Avoid undefined behaviour in drivers/scsi/sym53c8xx_2/sym_hipd.c:762

FromHelge Deller <deller@gmx.de>
Date2017-08-10 21:10 +0200
Subject[PATCH] sym53c8xx: Avoid undefined behaviour in drivers/scsi/sym53c8xx_2/sym_hipd.c:762
Message-ID<ud10e-1xP-19@gated-at.bofh.it>
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@gmx.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;
 
 	/*

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#1709335

FromJohannes Thumshirn <jthumshirn@suse.de>
Date2017-08-11 09:30 +0200
Message-ID<udcyl-A7-11@gated-at.bofh.it>
In reply to#1708971
On Thu, Aug 10, 2017 at 09:08:49PM +0200, Helge Deller wrote:
> 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().
                            div64_ul() ^

Otherwise,
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>


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Johannes Thumshirn                                          Storage
jthumshirn@suse.de                                +49 911 74053 689
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HRB 21284 (AG Nürnberg)
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