netdev - RE: [PATCH net-next] liquidio: fix format truncation warning reported by gcc 7.1.1

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Wed, 27 Sep 2017 09:04:35 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Felix Manlunas' <felix.manlunas@...ium.com>,
        "davem@...emloft.net" <davem@...emloft.net>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "raghu.vatsavayi@...ium.com" <raghu.vatsavayi@...ium.com>,
        "derek.chickles@...ium.com" <derek.chickles@...ium.com>,
        "satananda.burla@...ium.com" <satananda.burla@...ium.com>
Subject: RE: [PATCH net-next] liquidio: fix format truncation warning
 reported by gcc 7.1.1

From: Felix Manlunas
> Sent: 26 September 2017 19:48
> gcc 7.1.1 with -Wformat-truncation reports these warnings:
> 
> drivers/net/ethernet/cavium/liquidio/lio_core.c: In function `octeon_setup_interrupt':
> drivers/net/ethernet/cavium/liquidio/lio_core.c:1003:41: warning: `%u' directive output may be
> truncated writing between 1 and 10 bytes into a region of size between 0 and 13 [-Wformat-truncation=]
>        INTRNAMSIZ, "LiquidIO%u-pf%u-rxtx-%u",
...
> Fix them by changing the type of the "i" local variable from int to short.

That probably adds pointless code bloat by forcing the compiler to
keep masking the value with 0xffff after every arithmetic operation.

About the only architecture that doesn't suffer the penalty is x86.

Until the compiler can correctly track the domain of values (and
be given hints about the domains) this warning is, IMHO, OTT.

	David