Date: Mon, 17 Feb 2003 11:46:10 +1100 (EST) From: Bruce Evans <bde@zeta.org.au> To: Alfred Perlstein <alfred@FreeBSD.org> Cc: Max Khon <fjoe@FreeBSD.org>, <src-committers@FreeBSD.org>, <cvs-src@FreeBSD.org>, <cvs-all@FreeBSD.org> Subject: Re: cvs commit: src/sys/kern sysv_shm.c Message-ID: <20030217111423.R3751-100000@gamplex.bde.org> In-Reply-To: <20030216161224.GE93252@elvis.mu.org>
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On Sun, 16 Feb 2003, Alfred Perlstein wrote: > * Max Khon <fjoe@FreeBSD.org> [030216 02:50] wrote: > > hi, there! > > > > On Sat, Feb 15, 2003 at 10:08:55PM -0800, Alfred Perlstein wrote: > > > > > alfred 2003/02/15 22:08:55 PST > > > > > > Modified files: > > > sys/kern sysv_shm.c > > > Log: > > > prevent overflow in shminfo.shmmax > > > > > > Revision Changes Path > > > 1.79 +5 -1 src/sys/kern/sysv_shm.c > > > http://cvsweb.FreeBSD.org/src/sys/kern/sysv_shm.c.diff?r1=1.78&r2=1.79 > > > > for() loop will never be executed > > calculations in for() loop also look suspicious > > GAh, thanks! The contents of the loop are still suspicious. I think the only effect of revs.1.79-1.80 is to risk undefined behaviour for overflow PAGE_MAX times instead of only once. Overflow checking of shminfo.shmmax isn't very useful. Most tunables have no sanity checking, and none have complete sanity checking. For shminfo.shmmax, users can get the same effect as overflow by setting kern.ipc.shmmaxpages to a too-small value. E.g., 0 gives the same result as 2^32/PAGE_SIZE after overflow, and overflow is benign on all supported machines so the effect is also the same. Bruce To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message
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