On Wed, Apr 29, 2020 at 03:44:20PM -0400, Daniele Buono wrote:
> SafeStack is a stack protection technique implemented in llvm. It is
> enabled with a -fsanitize flag.
> iotests are currently disabled when any -fsanitize option is used.
> Since SafeStack is useful on production environments, and its
> implementation may break the binary, filter it out when the check is
> performed, so that if SafeStack was the only -fsanitize option, iotests
> are still performed.

I can't parse this sentence. What does "its implementation may break the
binary" mean? Do you mean it's worth running tests with SafeStack
enabled because it exposes failures that go unnoticed without SafeStack?

> 
> Signed-off-by: Daniele Buono <dbuono@linux.vnet.ibm.com>
> ---
>  tests/check-block.sh | 12 +++++++++++-
>  1 file changed, 11 insertions(+), 1 deletion(-)
> 
> diff --git a/tests/check-block.sh b/tests/check-block.sh
> index ad320c21ba..8e29c868e5 100755
> --- a/tests/check-block.sh
> +++ b/tests/check-block.sh
> @@ -21,7 +21,17 @@ if grep -q "CONFIG_GPROF=y" config-host.mak 2>/dev/null ; then
>      exit 0
>  fi
>  
> -if grep -q "CFLAGS.*-fsanitize" config-host.mak 2>/dev/null ; then
> +# Disable tests with any sanitizer except for SafeStack
> +CFLAGS=$( grep "CFLAGS.*-fsanitize" config-host.mak 2>/dev/null )
> +SANITIZE_FLAGS=""
> +#Remove all occurrencies of -fsanitize=safe-stack
> +for i in ${CFLAGS}; do
> +        if [ "${i}" != "-fsanitize=safe-stack" ]; then
> +                SANITIZE_FLAGS="${SANITIZE_FLAGS} ${i}"
> +        fi
> +done
> +if echo ${SANITIZE_FLAGS} | grep -q "\-fsanitize" 2>/dev/null; then
> +    # Have a sanitize flag that is not allowed, stop
>      echo "Sanitizers are enabled ==> Not running the qemu-iotests."
>      exit 0
>  fi

The commit that disabled check-block.sh with sanitizers said:

  The sanitizers (especially the address sanitizer from Clang) are
  sometimes printing out warnings or false positives - this spoils
  the output of the iotests, causing some of the tests to fail.

It seems fine to allow SafeStack if check-block.sh currently passes with
it enabled. Does it pass and produce no extra output?

Stefan