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); 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.
> > 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); I suggest to use #if __ELF_WORD_SIZE == 32 or 64.
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