Date: Sat, 5 Nov 2011 21:45:53 +0200 From: Kostik Belousov <kostikbel@gmail.com> To: Mikolaj Golub <trociny@freebsd.org> Cc: freebsd-hackers@freebsd.org, Robert Watson <rwatson@freebsd.org> Subject: Re: "ps -e" without procfs(5) Message-ID: <20111105194553.GK50300@deviant.kiev.zoral.com.ua> In-Reply-To: <86ehxmjsza.fsf@kopusha.home.net> References: <20111016171005.GB50300@deviant.kiev.zoral.com.ua> <86aa8qozyx.fsf@kopusha.home.net> <20111025082451.GO50300@deviant.kiev.zoral.com.ua> <86aa8k2im0.fsf@kopusha.home.net> <20111031094948.GB50300@deviant.kiev.zoral.com.ua> <86vcr21agm.fsf@kopusha.home.net> <20111105135801.GT50300@deviant.kiev.zoral.com.ua> <86ehxmpogp.fsf@kopusha.home.net> <20111105154443.GB50300@deviant.kiev.zoral.com.ua> <86ehxmjsza.fsf@kopusha.home.net>
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--Epf9GrANMtiMvSmS Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sat, Nov 05, 2011 at 08:59:21PM +0200, Mikolaj Golub wrote: >=20 > On Sat, 5 Nov 2011 17:44:43 +0200 Kostik Belousov wrote: >=20 > >> KB> I think that the aux vector must be naturally aligned. You can r= eturn > >> KB> ENOEXEC early if vptr is not aligned. > >>=20 > >> Not sure I see what you mean. vptr for auxv is calculated just couple= lines > >> above, and I check the result here, in the part common for all vector= types. > KB> You do not check for the alignment. Am I wrong ? >=20 > I see now. If natural alignment means "addr % sizeof(aux) =3D=3D 0" then = the aux > vectors are not naturally aligned. After adding this check: >=20 > if (vptr % sizeof(aux) !=3D 0) > return (ENOEXEC); No, the natural alignment of the structure is the alignment of the most demanding member. So it is 4 bytes on 32bit, and 8 bytes on 64. >=20 > I started to observe many ENOEXEC errors. Adding printf showed that the > vectors are half size aligned. >=20 > On i386: >=20 > get_proc_vector(pid =3D getty[3442], type =3D 2): vptr (2143284876) % siz= eof(aux) (8) =3D 4) >=20 > On amd64: >=20 > get_proc_vector(pid =3D getty[2425], type =3D 2): vptr (140737488346568) = % sizeof(aux) (16) =3D 8) >=20 > Looking at exec_copyout_strings() from kern_exec.c, how destp is calculat= ed, I > think they are sizeof(char *) aligned. >=20 > Do you think it is worth adding the check for sizeof(char *) alignment? >=20 > if (vptr % (sizeof(char *) !=3D 0) > return (ENOEXEC); I suggest to use #if __ELF_WORD_SIZE =3D=3D 32 or 64. --Epf9GrANMtiMvSmS Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.18 (FreeBSD) iEYEARECAAYFAk61knAACgkQC3+MBN1Mb4jTLwCeN7ZGTs3fkzi2O2u4ekESbzyP xrMAni700mDgj4WYfQb0ZWWHVWGPkWeG =DPWn -----END PGP SIGNATURE----- --Epf9GrANMtiMvSmS--
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