NetBSD Problem Report #49927

From www@NetBSD.org  Sun May 24 14:13:59 2015
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Date: Sun, 24 May 2015 14:13:58 +0000 (UTC)
From: rmh@freebsd.org
Reply-To: rmh@freebsd.org
To: gnats-bugs@NetBSD.org
Subject: [PATCH] Avoid division by zero in auich(4)
X-Send-Pr-Version: www-1.0

>Number:         49927
>Category:       kern
>Synopsis:       [PATCH] Avoid division by zero in auich(4)
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    kern-bug-people
>State:          closed
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sun May 24 14:15:00 +0000 2015
>Closed-Date:    Tue May 31 06:14:27 +0000 2016
>Last-Modified:  Tue May 31 06:14:27 +0000 2016
>Originator:     Robert Millan
>Release:        HEAD
>Organization:
>Environment:
RUMP environment (on top of GNU/Linux host)
>Description:
Please consider the following fix for auich(4):

    Avoid division by zero

    As wait_us is calculated by polling an I/O register, it is possible
    in certain environments (e.g. emulated hardware) that its value is
    zero. That is, that the I/O poll loop exits in less than 1 &#956;s.

    The check avoids division by zero in such situation.

>How-To-Repeat:

>Fix:
diff --git a/sys/dev/pci/auich.c b/sys/dev/pci/auich.c
index b2adad1..6a52800 100644
--- a/sys/dev/pci/auich.c
+++ b/sys/dev/pci/auich.c
@@ -1723,6 +1723,13 @@ auich_calibrate(struct auich_softc *sc)

 	rnd_add_data(NULL, &wait_us, sizeof(wait_us), 1);

+	/* avoid division by 0 below */
+	if (wait_us == 0) {
+		printf("%s: abnormal zero delay during calibration\n",
+					 device_xname(sc->sc_dev));
+		return;
+	}
+
 	actual_48k_rate = (bytes * UINT64_C(250000)) / wait_us;

 	if (actual_48k_rate < 50000)

>Release-Note:

>Audit-Trail:
From: "Christos Zoulas" <christos@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/49927 CVS commit: src/sys/dev/pci
Date: Sun, 24 May 2015 10:56:57 -0400

 Module Name:	src
 Committed By:	christos
 Date:		Sun May 24 14:56:57 UTC 2015

 Modified Files:
 	src/sys/dev/pci: auich.c

 Log Message:
 PR/49927: Robert Millan: Avoid zerodivide on emulated hardware.


 To generate a diff of this commit:
 cvs rdiff -u -r1.146 -r1.147 src/sys/dev/pci/auich.c

 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.

State-Changed-From-To: open->closed
State-Changed-By: pgoyette@NetBSD.org
State-Changed-When: Tue, 31 May 2016 06:14:27 +0000
State-Changed-Why:
This was fixed by Christos@ on May 24 14:56:57 UTC 2015


>Unformatted:

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