"ps -e" without procfs(5)
Mikolaj Golub
trociny at freebsd.org
Wed Nov 2 21:27:45 UTC 2011
On Mon, 31 Oct 2011 11:49:48 +0200 Kostik Belousov wrote:
KB> I think it is better to use sys/elf.h over the machine/elf.h.
KB> Please change the comment for PROC_AUXV_MAX to "Safety limit on auxv size".
KB> Also, it worth adding a comment saying that we are reading aux vectors twice,
KB> first to get a size, second time to fetch a content, for simplicity.
KB> When reading aux vector, if the PROC_AUXV_MAX entries are iterated over,
KB> and we still not reached AT_NULL, the return error is 0. Was it intended ?
KB> For PROC_ARG and PROC_ENV, you blindly trust the read values of the arg and
KB> env vector sizes. This can easily cause kernel panics due to unability to
KB> malloc the requested memory. I recommend to put some clump, and twice
KB> of (PATH_MAX + ARG_MAX) is probably enough (see kern_exec.c, in particular,
KB> exec_alloc_args). Also, you might use the swappable memory for the strings
KB> as well, in the style of exec_alloc_args().
KB> I suspect this is my bug: Reading the GET_PS_STRINGS_CHUNK_SZ may validly
KB> return EFAULT if the string is shorter than the chunk and aligned at
KB> the end of the page, assuming the next page is not mapped. There should
KB> be a fallback to fubyte() read loop. I remember that copyinstr() was
KB> unsuitable.
KB> The checks for P_WEXIT in the linprocfs routines look strange. Since
KB> you are unlocking the process right after the check, it does not make
KB> sense. In fact, the checks are not needed, I believe, since pseudofs
KB> already did the hold (see e.g. pfs_read and pfs_visible).
Here is an updated version of the patch. Also available at
http://people.freebsd.org/~trociny/env.sys.1.patch
I decided to use the same constant (PROC_VECTOR_MAX) for limiting both the number
of arg or env strings and the numbex of aux vectors.
Also I decided not to play with exec_alloc_args :-).
--
Mikolaj Golub
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