Date: Sat, 05 Nov 2011 22:37:46 +0200 From: Mikolaj Golub <trociny@freebsd.org> To: Kostik Belousov <kostikbel@gmail.com> Cc: freebsd-hackers@freebsd.org, Robert Watson <rwatson@freebsd.org> Subject: Re: "ps -e" without procfs(5) Message-ID: <8662iyjof9.fsf@kopusha.home.net> In-Reply-To: <20111105194553.GK50300@deviant.kiev.zoral.com.ua> (Kostik Belousov's message of "Sat, 5 Nov 2011 21:45:53 %2B0200") 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> <20111105194553.GK50300@deviant.kiev.zoral.com.ua>
next in thread | previous in thread | raw e-mail | index | archive | help
On Sat, 5 Nov 2011 21:45:53 +0200 Kostik Belousov wrote: KB> On Sat, Nov 05, 2011 at 08:59:21PM +0200, Mikolaj Golub wrote: >> >> On Sat, 5 Nov 2011 17:44:43 +0200 Kostik Belousov wrote: >> >> >> KB> I think that the aux vector must be naturally aligned. You can return >> >> KB> ENOEXEC early if vptr is not aligned. >> >> >> >> 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 ? >> >> I see now. If natural alignment means "addr % sizeof(aux) == 0" then the aux >> vectors are not naturally aligned. After adding this check: >> >> if (vptr % sizeof(aux) != 0) >> return (ENOEXEC); KB> No, the natural alignment of the structure is the alignment of the most KB> demanding member. So it is 4 bytes on 32bit, and 8 bytes on 64. >> >> I started to observe many ENOEXEC errors. Adding printf showed that the >> vectors are half size aligned. >> >> On i386: >> >> get_proc_vector(pid = getty[3442], type = 2): vptr (2143284876) % sizeof(aux) (8) = 4) >> >> On amd64: >> >> get_proc_vector(pid = getty[2425], type = 2): vptr (140737488346568) % sizeof(aux) (16) = 8) >> >> Looking at exec_copyout_strings() from kern_exec.c, how destp is calculated, I >> think they are sizeof(char *) aligned. >> >> Do you think it is worth adding the check for sizeof(char *) alignment? >> >> if (vptr % (sizeof(char *) != 0) >> return (ENOEXEC); KB> I suggest to use #if __ELF_WORD_SIZE == 32 or 64. Thanks. The updated patch: http://people.freebsd.org/~trociny/env.sys.3.patch -- Mikolaj Golub
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?8662iyjof9.fsf>