Sounds good! I think the manpage still might still need a change to match the current behavior, or perhaps matching something similar to that vm_mmap.c comment. But that comment brings another question: what's the definition of "old binaries"? a.out?
Thanks, -- Shawn Webb Cofounder / Security Engineer HardenedBSD Tor-ified Signal: +1 443-546-8752 Tor+XMPP+OTR: latt...@is.a.hacker.sx GPG Key ID: 0xFF2E67A277F8E1FA GPG Key Fingerprint: D206 BB45 15E0 9C49 0CF9 3633 C85B 0AF8 AB23 0FB2 On Mon, Jun 10, 2019 at 09:19:55AM -0500, Doug Moore wrote: > This comment appears in vm_mmap.c: > > ???? * Mapping of length 0 is only allowed for old binaries. > > and my intent was to say, to whoever wrote that comment, that I was not > disallowing the mapping of length zero with this change.? I was only > intending to affect a case in which the length was transformed to zero, > and which was the problem that Peter Holm reported. > > Doug Moore > > On 6/10/19 8:00 AM, Shawn Webb wrote: > > On Mon, Jun 10, 2019 at 03:07:11AM +0000, Doug Moore wrote: > >> Author: dougm > >> Date: Mon Jun 10 03:07:10 2019 > >> New Revision: 348843 > >> URL: https://svnweb.freebsd.org/changeset/base/348843 > >> > >> Log: > >> There are times when a len==0 parameter to mmap is okay. But on a > >> 32-bit machine, a len parameter just a few bytes short of 4G, rounded > >> up to a page boundary and hitting zero then, is not okay. Return > >> failure in that case. > >> > >> Reported by: pho > >> Reviewed by: alc, kib (mentor) > >> Tested by: pho > >> Differential Revision: https://reviews.freebsd.org/D20580 > >> > >> Modified: > >> head/sys/vm/vm_mmap.c > >> > >> Modified: head/sys/vm/vm_mmap.c > >> ============================================================================== > >> --- head/sys/vm/vm_mmap.c Sun Jun 9 22:55:21 2019 (r348842) > >> +++ head/sys/vm/vm_mmap.c Mon Jun 10 03:07:10 2019 (r348843) > >> @@ -257,7 +257,10 @@ kern_mmap(struct thread *td, uintptr_t addr0, size_t s > >> > >> /* Adjust size for rounding (on both ends). */ > >> size += pageoff; /* low end... */ > >> - size = (vm_size_t) round_page(size); /* hi end */ > >> + /* Check for rounding up to zero. */ > >> + if (round_page(size) < size) > >> + return (EINVAL); > > The mmap(2) manpage says that len==0 results in EINVAL, so the manpage > > needs updating. > > > > I'm curious what "there are times" refers to. Can you or the original > > reporter elaborate those cases? > > > > Thanks a lot! > >
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