Date: Tue, 21 Mar 2017 17:53:12 +0200 From: Toomas Soome <tsoome@me.com> To: Ian Lepore <ian@freebsd.org> Cc: Slawa Olhovchenkov <slw@zxy.spb.ru>, Toomas Soome <tsoome@FreeBSD.org>, src-committers <src-committers@freebsd.org>, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r315653 - in head: lib/libstand sys/boot/common sys/boot/i386/libi386 Message-ID: <EBAA7588-B735-438A-A851-77A8B7DC63CC@me.com> In-Reply-To: <1490109312.13094.41.camel@freebsd.org> References: <201703202220.v2KMKHVP050735@repo.freebsd.org> <20170321123547.GC86500@zxy.spb.ru> <1490109312.13094.41.camel@freebsd.org>
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> On 21. m=C3=A4rts 2017, at 17:15, Ian Lepore <ian@freebsd.org> wrote: >=20 > On Tue, 2017-03-21 at 15:35 +0300, Slawa Olhovchenkov wrote: >> On Mon, Mar 20, 2017 at 10:20:17PM +0000, Toomas Soome wrote: >>=20 >>>=20 >>> Author: tsoome >>> Date: Mon Mar 20 22:20:17 2017 >>> New Revision: 315653 >>> URL: https://svnweb.freebsd.org/changeset/base/315653 >>>=20 >>> Log: >>> loader: verify the value from dhcp.interface-mtu and use snprintf >>> to set mtu >>> =20 >>> Since the uset can set dhcp.interface-mtu, we need to try to >>> validate the >>> value. So we verify if the conversion to int is successful and we >>> will not >>> allow to set value greater than max IPv4 packet size. >>> =20 >>> + tmp > USHRT_MAX) { >>> + printf("%s: bad value: >>> \"%s\", " >>> + "ignoring\n", >>> + "dhcp.interface-mtu", >>> val); >> =3D=3D=3D >> USHRT_MAX Maximum value for an object of type unsigned short >> int >> 65535 (216-1) or greater* >>=20 >> * the actual value depends on the particular system and library >> implementation, but shall reflect the limits of these types in the >> target platform. >> =3D=3D=3D >>=20 >> I mean IF_MAXMTU more correct. >>=20 >=20 > The context here is libstand; because it is standalone by design, the > code doesn't have access to IF_MAXMTU or other kernel/userland > constants. There is also no question that a short is 16 bits or that > USHRT_MAX will be anything other than 65535 in that environment. If > some platform did appear that had a different-sized short by default, > we would add whatever flags are necessary to force it back to 16 bits > in src/share/mk/bsd.stand.mk. >=20 Also note the =E2=80=9Cupper=E2=80=9D value is entirely fictional - we = felt we need to pick some =E2=80=9Csane=E2=80=9D default, with current = (common 1Gb/s) ethernet hardware you will be in trouble long before = reaching that value;) rgds, toomas
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