"ps -e" without procfs(5)

[Mikolaj Golub]

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);

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);

-- 
Mikolaj Golub