[LTP] [PATCH] lib: tst_taint: Ignore WARN taint flag if already set

[Michael Moese]

Hi,

On 16.10.19 15:15, Cyril Hrubis wrote:
> This commit changes the library so that it ignores the taint warn flag
> if it was set prior to the test run. It turns out that the warn taint
> flag is not well defined and could be easily set on a freshly booted
> kernel for example when buggy BIOS is detected.>
> Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
> CC: Jan Stancek <jstancek@redhat.com>
> CC: Chang Yin <cyin@redhat.com>
> ---
> 
> I haven't tested this, since I don't have a system where the flag is set
> at hand, but it's simple enough so that it should work as expected.
> 
>  lib/tst_taint.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/lib/tst_taint.c b/lib/tst_taint.c
> index a5dbf77d2..3de6d72f4 100644
> --- a/lib/tst_taint.c
> +++ b/lib/tst_taint.c
> @@ -82,8 +82,13 @@ void tst_taint_init(unsigned int mask)
>  		tst_res(TCONF, "Kernel is too old for requested mask");
>  
>  	taint_mask = mask;
> -
>  	taint = tst_taint_read();
> +
> +	if (mask & TST_TAINT_W && taint & TST_TAINT_W) {
> +		tst_res(TCONF, "Ignoring already set kernel warning taint");
> +		mask &= ~TST_TAINT_W;
> +	}
> +
>  	if ((taint & mask) != 0)
>  		tst_brk(TBROK, "Kernel is already tainted: %u", taint);
>  }
> 

Tests may rely on TAINT_W to decide the result. If we need TAINT_W, we
can only run the test when it was not set before. For example,
testcases/cve/cve-2017-17053.c relies on this.
This may render this testcase unusable, or do I get this wrong?

-- 
Michael Moese <mmoese@suse.de>
QA Engineer
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