Date: Sun, 4 Apr 2004 23:20:10 -0500 From: Alan Cox <alc@cs.rice.edu> To: Alexander Kabaev <ak03@gte.com> Cc: current@freebsd.org Subject: Re: mmap breakage? Message-ID: <20040405042010.GQ15786@cs.rice.edu> In-Reply-To: <20040405041147.GA39962@kanpc.gte.com> References: <20040402191254.GK26131@elvis.mu.org> <35917.1080933274@critter.freebsd.dk> <20040402195957.GN26131@elvis.mu.org> <20040404201251.GP15786@cs.rice.edu> <20040405041147.GA39962@kanpc.gte.com>
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On Mon, Apr 05, 2004 at 12:11:47AM -0400, Alexander Kabaev wrote: > On Sun, Apr 04, 2004 at 03:12:51PM -0500, Alan Cox wrote: > > Alfred, > > > > Please try the attached patch. This problems appears to be a > > consequence of vm/vm_mmap.c revision 1.180, where as part of a much > > needed code reorganization for locking the check for the /dev/zero > > special case got placed after the permissions check for the general > > case. This patch simply delays the permissions check for devices > > until you have the necessary lock to also check for /dev/zero. > > > > Since kan@ authored the reorganization, I'm cc:'ing him on this > > message for purposes of obtaining a review. (At least one comment > > should be updated to reflect my code changes.) > > > > Regards, > > Alan > > > > > Alan, Alfred, > > I had the following patch which is currently pending a review by > Peter Wemm. I meant to commit it on Friday, but ran out of time: > > > http://perforce.freebsd.org/chv.cgi?CH=50213 > I believe that there is a problem with this patch. Specifically, if maxprot is set to VM_PROT_ALL for devices in mmap(), then the security check in vm_mmap_vnode() has no effect. Please take a look at the entirety of the changes that I propose to mmap(). Regards, Alan
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