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 _______________________________________________ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "freebsd-hackers-unsubscr...@freebsd.org"
