Date: Wed, 12 Jun 2019 21:09:30 +0000 From: Brooks Davis <brooks@freebsd.org> To: Shawn Webb <shawn.webb@hardenedbsd.org> Cc: Doug Moore <dougm@FreeBSD.org>, src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org, pho@freebsd.org Subject: Re: svn commit: r348843 - head/sys/vm Message-ID: <20190612210930.GK64641@spindle.one-eyed-alien.net> In-Reply-To: <20190610130034.k2nzitvaxvpj5lzx@mutt-hbsd> References: <201906100307.x5A37BFt099669@repo.freebsd.org> <20190610130034.k2nzitvaxvpj5lzx@mutt-hbsd>
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--mhOzvPhkurUs4vA9 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Jun 10, 2019 at 09:00:34AM -0400, 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 > >=20 > > Log: > > There are times when a len=3D=3D0 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. > > =20 > > Reported by: pho > > Reviewed by: alc, kib (mentor) > > Tested by: pho > > Differential Revision: https://reviews.freebsd.org/D20580 > >=20 > > Modified: > > head/sys/vm/vm_mmap.c > >=20 > > Modified: head/sys/vm/vm_mmap.c > > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D > > --- 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 > > =20 > > /* Adjust size for rounding (on both ends). */ > > size +=3D pageoff; /* low end... */ > > - size =3D (vm_size_t) round_page(size); /* hi end */ > > + /* Check for rounding up to zero. */ > > + if (round_page(size) < size) > > + return (EINVAL); >=20 > The mmap(2) manpage says that len=3D=3D0 results in EINVAL, so the manpage > needs updating. The manpage is correct for ABIs people are actually writing code for (ELF). I suppose it could document the exception for a.out (see the conditional containing SV_CURPROC_FLAG(SV_AOUT) in kern_mmap()), but it should be in BUGS, HISTORY, or some such. -- Brooks --mhOzvPhkurUs4vA9 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEcBAEBAgAGBQJdAWoKAAoJEKzQXbSebgfAd5wIAJ8q1Nv3uNJSB2JZkCfk8rSr 7D8CpRyHqrzP1+ew7QrW8r53gqExbnwki01IloB9v27TuCmTALmDMpQFQalAHXsi yrFlO/YuyhMW+Zfnrv6ym6PoYV6KzyoHN7W2r30ObKkJG4mqfjU6PWrKp8A1eIoh VJYzlcbcXWooDTG5l1MIAeEVaxziUN61+WtXBsj5mBQd3ionbpJP9kMZxoMCbbqb 0iI+YJUETCLIF/BS6EcnIOJpVTChobJ5hk1LIOqRfU/I4uo+d1ThRbX+pYJy/TkS 03X5pcxKd5f6MPxvPZp2N2RB5rWizWj/HHzgLMoEyg1J34TR0/d5GmQk7h9DLaU= =kkOR -----END PGP SIGNATURE----- --mhOzvPhkurUs4vA9--
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