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

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Date:   Sat, 27 Jul 2019 10:36:03 +0200
From:   Jiri Pirko <jiri@...nulli.us>
To:     Stephen Hemminger <stephen@...workplumber.org>
Cc:     chrims@...lanox.com, 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

Fri, Jul 26, 2019 at 09:47:07PM CEST, stephen@...workplumber.org wrote:
>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.

I agree. This is a mess :(


>
>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