netdev - Re: [patch iproute2 1/2] tc: action: fix crash caused by incorrect *argv check

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Date:   Fri, 26 Jul 2019 12:47:07 -0700
From:   Stephen Hemminger <stephen@...workplumber.org>
To:     Jiri Pirko <jiri@...nulli.us>, chrims@...lanox.com
Cc:     netdev@...r.kernel.org, sthemmin@...rosoft.com, dsahern@...il.com,
        alexanderk@...lanox.com, mlxsw@...lanox.com
Subject: Re: [patch iproute2 1/2] tc: action: fix crash caused by incorrect
 *argv check

On Tue, 23 Jul 2019 13:25:37 +0200
Jiri Pirko <jiri@...nulli.us> wrote:

> From: Jiri Pirko <jiri@...lanox.com>
> 
> One cannot depend on *argv being null in case of no arg is left on the
> command line. For example in batch mode, this is not always true. Check
> argc instead to prevent crash.
> 
> Reported-by: Alex Kushnarov <alexanderk@...lanox.com>
> Fixes: fd8b3d2c1b9b ("actions: Add support for user cookies")
> Signed-off-by: Jiri Pirko <jiri@...lanox.com>
> ---
>  tc/m_action.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tc/m_action.c b/tc/m_action.c
> index ab6bc0ad28ff..0f9c3a27795d 100644
> --- a/tc/m_action.c
> +++ b/tc/m_action.c
> @@ -222,7 +222,7 @@ done0:
>  				goto bad_val;
>  			}
>  
> -			if (*argv && strcmp(*argv, "cookie") == 0) {
> +			if (argc && strcmp(*argv, "cookie") == 0) {
>  				size_t slen;
>  
>  				NEXT_ARG();


The logic here is broken at end of file.

	do {
		if (getcmdline(&line_next, &len, stdin) == -1)
			lastline = true;

		largc_next = makeargs(line_next, largv_next, 100);
		bs_enabled_next = batchsize_enabled(largc_next, largv_next);
		if (bs_enabled) {
			struct batch_


getcmdline() will return -1 at end of file.
The code will call make_args on an uninitialized pointer.

I see lots of other unnecessary complexity in the whole batch logic.
It needs to be rewritten.

Rather than me fixing the code, I am probably going to revert.

commit 485d0c6001c4aa134b99c86913d6a7089b7b2ab0
Author: Chris Mi <chrism@...lanox.com>
Date:   Fri Jan 12 14:13:16 2018 +0900

    tc: Add batchsize feature for filter and actions