Re: [dpdk-stable] [PATCH] app/test-compress-perf: fix reliance on integer endianness

["Trahe, Fiona" <fiona.trahe@intel.com>]

Hi Shally, Tomasz,

> > > > > -----Original Message-----
> > > > > From: Jozwiak, TomaszX
> > > > > Sent: Monday, May 20, 2019 2:26 PM
> > > > > To: dev@dpdk.org; Trahe, Fiona <fiona.trahe@intel.com>; Jozwiak,
> > > > > TomaszX <tomaszx.jozwiak@intel.com>; shallyv@marvell.com;
> > > > > stable@dpdk.org
> > > > > Subject: [PATCH] app/test-compress-perf: fix reliance on integer
> > > > > endianness
> > > > >
> > > > > This patch fixes coverity issue:
> > > > > Reliance on integer endianness (INCOMPATIBLE_CAST) in
> > > > parse_window_sz
> > > > > function.
> > > > >
> > > > > Coverity issue: 328524
> > > > > Fixes: e0b6287c035d ("app/compress-perf: add parser")
> > > > > Cc: stable@dpdk.org
> > > > >
> > > > > Signed-off-by: Tomasz Jozwiak <tomaszx.jozwiak@intel.com>
> > > > > ---
> > > > >  app/test-compress-perf/comp_perf_options_parse.c | 4 +++-
> > > > >  1 file changed, 3 insertions(+), 1 deletion(-)
> > > > >
> > > > > diff --git a/app/test-compress-perf/comp_perf_options_parse.c
> > > > > b/app/test-compress- perf/comp_perf_options_parse.c index
> > > > > 2fb6fb4..56ca580 100644
> > > > > --- a/app/test-compress-perf/comp_perf_options_parse.c
> > > > > +++ b/app/test-compress-perf/comp_perf_options_parse.c
> > > > > @@ -364,13 +364,15 @@ parse_max_num_sgl_segs(struct
> > > > comp_test_data
> > > > > *test_data, const char *arg)  static int  parse_window_sz(struct
> > > > > comp_test_data *test_data, const char *arg)  {
> > > > > -	int ret = parse_uint16_t((uint16_t *)&test_data->window_sz, arg);
> > > > > +	uint16_t tmp;
> > > > > +	int ret = parse_uint16_t(&tmp, arg);
> > > > >
> > > > >  	if (ret) {
> > > > >  		RTE_LOG(ERR, USER1, "Failed to parse window size\n");
> > > > >  		return -1;
> > > > >  	}
> > > > >
> > > > > +	test_data->window_sz = (int)tmp;
> > > > >  	return 0;
> > > > >  }
> > > > [Fiona] I expect this fixes this coverity issue - but will it result in another
> > one?
> > > > window_sz on the xform is uint8_t - so this int will get truncated
> > > > later, and there's no cast done at that point.
> > > > Would it be better to add a new parse_uint8_t fn and change
> > > > test-data-
> > > > >window_sz to a unit8_t?
> > > > Or add that cast?
> > > [Tomek] I measn it's ok. There's a check inside
> > > comp_perf_check_capabilities function.
> > > If the value from test_data->window_sz > cap->window_size we have a
> > fail.
> > > Also during parsing there's a check is value from command line between
> > > 0 and UINT16_MAX, so in my opinion all cases are tested. The point is
> > > there's only one place where we're parsing uint8_t value.
> > > parse_uint8_t function will be especially for that.
> > [Shally] What is window_sz in test data ?is it base 2 log of (actual window
> > length) or actual window length in bytes? lib spec mention this as struct
> > rte_param_log2_range, so If test window size is actual window length in
> > bytes then I assume test perf should check for test_data->window_sz > 2
> > pow cap->window_size but that doesn't look like the case.
> > So if it is log value, then coding wise typecasting here doesn't look right.
> > Though it add need for extra function to parse_uint8, but that looks like
> > cleaner approach to use.
> [Tomek] I mean it's log 2  (please take a look at help usage function in comp_perf_options_parse.c:37
> 
> " --window-sz N: base two log value of compression window size\n"
> 		"		(e.g.: 15 => 32k, default: max supported by PMD)\n"
> 
> I mean it's ok, still. We have many types in command line and can be much more in the future. The idea
> is to parse them into a sort of common range value first ( it should be max range for all digital command
> line options - in our case there's uint16 or uint32_t) even if it's shorter like uint8_t or etc. We store
> these values in comp_test_data structure first. Next we check the ranges each of them. In case of
> window_sz this test is in comp_perf_check_capabilities function. That approach reduce a  set of parsing
> functions we needed. Of course we can create separate parsing function for each of command line type
> value, but is this really needed ? :D
> Please let me know your thoughts - if this new parsing function will clear the code - I'll add this in v2
[Fiona] ok, I reviewed again and see I'd misunderstood.
The param being parsed is intentionally not being stored in test_data struct as uint8_t, but as
an int because it uses -1 as a default value. And there are range checks on the input, so an invalid value will never be passed to the PMD.  
So I'm ok with the fix as is - it resolves the coverity issues reported on the param parsing.

However there's a second issue, which coverity is likely to throw up after the above fix is applied - when
the test_data value is later passed to the PMD, it should have a cast from int to unit8_t. 
But that's a separate issue, not referred to by this coverity report, so we'll send a separate patch for it.
@Shally, are you ok with this?