NetBSD Problem Report #50911

From www@NetBSD.org  Mon Mar  7 12:23:24 2016
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Date: Mon,  7 Mar 2016 12:23:23 +0000 (UTC)
From: dcb314@hotmail.com
Reply-To: dcb314@hotmail.com
To: gnats-bugs@NetBSD.org
Subject: src/usr.sbin/makefs/chfs/chfs_mkfs.c:134: clumsy call to memset ?
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>Number:         50911
>Category:       bin
>Synopsis:       src/usr.sbin/makefs/chfs/chfs_mkfs.c:134: clumsy call to memset ?
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    bin-bug-people
>State:          closed
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Mar 07 12:25:00 +0000 2016
>Closed-Date:    Mon Mar 07 16:10:59 +0000 2016
>Last-Modified:  Mon Mar 07 16:10:59 +0000 2016
>Originator:     David Binderman
>Release:        cvs dated 20160305
>Organization:
>Environment:
>Description:

[src/usr.sbin/makefs/chfs/chfs_mkfs.c:127] -> [src/usr.sbin/makefs/chfs/chfs_mkfs.c:134]: (performance) Buffer 'buf' is being written before its old content has been used.

Source code is

    memset(buf, 0xFF, opts->pagesize);

    ebhdr.ec_hdr.magic = htole32(CHFS_MAGIC_BITMASK);
    ebhdr.ec_hdr.erase_cnt = htole32(1);
    ebhdr.ec_hdr.crc_ec = htole32(crc32(0,
        (uint8_t *)&ebhdr.ec_hdr + 8, 4));

    memcpy(buf, &ebhdr.ec_hdr, CHFS_EB_EC_HDR_SIZE);


Maybe better code



    ebhdr.ec_hdr.magic = htole32(CHFS_MAGIC_BITMASK);
    ebhdr.ec_hdr.erase_cnt = htole32(1);
    ebhdr.ec_hdr.crc_ec = htole32(crc32(0,
        (uint8_t *)&ebhdr.ec_hdr + 8, 4));

    memcpy(buf, &ebhdr.ec_hdr, CHFS_EB_EC_HDR_SIZE);
    memset(buf + CHFS_EB_EC_HDR_SIZE, 0xFF, opts->pagesize - CHFS_EB_EC_HDR_SIZE);

>How-To-Repeat:

>Fix:

>Release-Note:

>Audit-Trail:
From: "Christos Zoulas" <christos@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/50911 CVS commit: src/usr.sbin/makefs/chfs
Date: Mon, 7 Mar 2016 10:58:05 -0500

 Module Name:	src
 Committed By:	christos
 Date:		Mon Mar  7 15:58:05 UTC 2016

 Modified Files:
 	src/usr.sbin/makefs/chfs: chfs_mkfs.c

 Log Message:
 PR/50911: David Binderman: Optimize memset


 To generate a diff of this commit:
 cvs rdiff -u -r1.6 -r1.7 src/usr.sbin/makefs/chfs/chfs_mkfs.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: wiz@NetBSD.org
State-Changed-When: Mon, 07 Mar 2016 16:10:59 +0000
State-Changed-Why:
Fixed by christos, thanks!


>Unformatted:

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