Some environments do not set $SHELL when running tests. There's no need to use $SHELL here anyway, since "cat" can be used to receive any delivered signals from the kernel. Additionally avoid using bash-isms in the command, and record stderr for posterity.

Suggested-by: Guillaume Tucker guillaume.tucker@collabora.com Suggested-by: David Laight David.Laight@ACULAB.COM Fixes: 46d1a0f03d66 ("selftests/lkdtm: Add tests for LKDTM targets") Cc: stable@vger.kernel.org Signed-off-by: Kees Cook keescook@chromium.org --- tools/testing/selftests/lkdtm/run.sh | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/tools/testing/selftests/lkdtm/run.sh b/tools/testing/selftests/lkdtm/run.sh index bb7a1775307b..e95e79bd3126 100755 --- a/tools/testing/selftests/lkdtm/run.sh +++ b/tools/testing/selftests/lkdtm/run.sh @@ -76,10 +76,14 @@ fi # Save existing dmesg so we can detect new content below dmesg > "$DMESG"

-# Most shells yell about signals and we're expecting the "cat" process -# to usually be killed by the kernel. So we have to run it in a sub-shell -# and silence errors. -($SHELL -c 'cat <(echo '"$test"') >'"$TRIGGER" 2>/dev/null) || true +# Since the kernel is likely killing the process writing to the trigger +# file, it must not be the script's shell itself. i.e. we cannot do: +# echo "$test" >"$TRIGGER" +# Instead, use "cat" to take the signal. Since the shell will yell about +# the signal that killed the subprocess, we must ignore the failure and +# continue. However we don't silence stderr since there might be other +# useful details reported there in the case of other unexpected conditions. +echo "$test" | cat >"$TRIGGER" || true

# Record and dump the results dmesg | comm --nocheck-order -13 "$DMESG" - > "$LOG" || true